Merge branch 'mc1.15/dev' into mc1.15/ponder-ui

src/generated/resources/assets/create/lang/en_us.json

@@ -822,6 +822,12 @@
 	"create.gui.goggles.kinetic_stats": "Kinetic Stats:",
 	"create.gui.goggles.at_current_speed": "at current speed",
 	"create.gui.goggles.pole_length": "Pole Length:",
+	"create.gui.assembly.exception": "This Contraption was unable to assemble:",
+	"create.gui.assembly.exception.unmovableBlock": "Unmovable Block (%4$s) at [%1$s %2$s %3$s]",
+	"create.gui.assembly.exception.chunkNotLoaded": "The Block at [%1$s %2$s %3$s] was not in a loaded chunk",
+	"create.gui.assembly.exception.structureTooLarge": "There are too many Blocks included in the contraption.\nThe configured maximum is: %1$s",
+	"create.gui.assembly.exception.tooManyPistonPoles": "There are too many extension Poles attached to this Piston.\nThe configured maximum is: %1$s",
+	"create.gui.assembly.exception.noPistonPoles": "The Piston is missing some extension Poles",
 	"create.gui.gauge.info_header": "Gauge Information:",
 	"create.gui.speedometer.title": "Rotation Speed",
 	"create.gui.stressometer.title": "Network Stress",

src/generated/resources/assets/create/lang/unfinished/de_de.json

@@ -823,6 +823,12 @@
 	"create.gui.goggles.kinetic_stats": "UNLOCALIZED: Kinetic Stats:",
 	"create.gui.goggles.at_current_speed": "UNLOCALIZED: at current speed",
 	"create.gui.goggles.pole_length": "UNLOCALIZED: Pole Length:",
+	"create.gui.assembly.exception": "UNLOCALIZED: This Contraption was unable to assemble:",
+	"create.gui.assembly.exception.unmovableBlock": "UNLOCALIZED: Unmovable Block (%4$s) at [%1$s %2$s %3$s]",
+	"create.gui.assembly.exception.chunkNotLoaded": "UNLOCALIZED: The Block at [%1$s %2$s %3$s] was not in a loaded chunk",
+	"create.gui.assembly.exception.structureTooLarge": "UNLOCALIZED: There are too many Blocks included in the contraption.\nThe configured maximum is: %1$s",
+	"create.gui.assembly.exception.tooManyPistonPoles": "UNLOCALIZED: There are too many extension Poles attached to this Piston.\nThe configured maximum is: %1$s",
+	"create.gui.assembly.exception.noPistonPoles": "UNLOCALIZED: The Piston is missing some extension Poles",
 	"create.gui.gauge.info_header": "UNLOCALIZED: Gauge Information:",
 	"create.gui.speedometer.title": "UNLOCALIZED: Rotation Speed",
 	"create.gui.stressometer.title": "UNLOCALIZED: Network Stress",

src/main/java/com/simibubi/create/content/contraptions/base/GeneratingKineticTileEntity.java

@@ -38,7 +38,7 @@ public abstract class GeneratingKineticTileEntity extends KineticTileEntity {
 		if (!(tileEntity instanceof KineticTileEntity))
 			return;
 		KineticTileEntity sourceTe = (KineticTileEntity) tileEntity;
-		if (reActivateSource && sourceTe != null && Math.abs(sourceTe.getSpeed()) >= Math.abs(getGeneratedSpeed()))
+		if (reActivateSource && Math.abs(sourceTe.getSpeed()) >= Math.abs(getGeneratedSpeed()))
 			reActivateSource = false;
 	}
 

src/main/java/com/simibubi/create/content/contraptions/components/structureMovement/AssemblyException.java

@@ -0,0 +1,91 @@
+package com.simibubi.create.content.contraptions.components.structureMovement;
+
+import com.simibubi.create.foundation.config.AllConfigs;
+import net.minecraft.block.BlockState;
+import net.minecraft.nbt.CompoundNBT;
+import net.minecraft.util.math.BlockPos;
+import net.minecraft.util.text.ITextComponent;
+import net.minecraft.util.text.TranslationTextComponent;
+
+public class AssemblyException extends Exception {
+	public final ITextComponent component;
+	private BlockPos position = null;
+
+	public static void write(CompoundNBT compound, AssemblyException exception) {
+		if (exception == null)
+			return;
+
+		CompoundNBT nbt = new CompoundNBT();
+		nbt.putString("Component", ITextComponent.Serializer.toJson(exception.component));
+		if (exception.hasPosition())
+			nbt.putLong("Position", exception.getPosition().toLong());
+
+		compound.put("LastException", nbt);
+	}
+
+	public static AssemblyException read(CompoundNBT compound) {
+		if (!compound.contains("LastException"))
+			return null;
+
+		CompoundNBT nbt = compound.getCompound("LastException");
+		String string = nbt.getString("Component");
+		AssemblyException exception = new AssemblyException(ITextComponent.Serializer.fromJson(string));
+		if (nbt.contains("Position"))
+			exception.position = BlockPos.fromLong(nbt.getLong("Position"));
+
+		return exception;
+	}
+
+	public AssemblyException(ITextComponent component) {
+		this.component = component;
+	}
+
+	public AssemblyException(String langKey, Object... objects) {
+		this(new TranslationTextComponent("create.gui.assembly.exception." + langKey, objects));
+	}
+
+	public static AssemblyException unmovableBlock(BlockPos pos, BlockState state) {
+		AssemblyException e = new AssemblyException("unmovableBlock",
+				pos.getX(),
+				pos.getY(),
+				pos.getZ(),
+				new TranslationTextComponent(state.getBlock().getTranslationKey()));
+		e.position = pos;
+		return e;
+	}
+
+	public static AssemblyException unloadedChunk(BlockPos pos) {
+		AssemblyException e = new AssemblyException("chunkNotLoaded",
+				pos.getX(),
+				pos.getY(),
+				pos.getZ());
+		e.position = pos;
+		return e;
+	}
+
+	public static AssemblyException structureTooLarge() {
+		return new AssemblyException("structureTooLarge",
+				AllConfigs.SERVER.kinetics.maxBlocksMoved.get());
+	}
+
+	public static AssemblyException tooManyPistonPoles() {
+		return new AssemblyException("tooManyPistonPoles",
+				AllConfigs.SERVER.kinetics.maxPistonPoles.get());
+	}
+
+	public static AssemblyException noPistonPoles() {
+		return new AssemblyException("noPistonPoles");
+	}
+
+	public String getFormattedText() {
+		return component.getFormattedText();
+	}
+
+	public boolean hasPosition() {
+		return position != null;
+	}
+
+	public BlockPos getPosition() {
+		return position;
+	}
+}

src/main/java/com/simibubi/create/content/contraptions/components/structureMovement/BlockMovementTraits.java

@@ -53,8 +53,7 @@ import net.minecraft.world.World;
 
 public class BlockMovementTraits {
 
-	public static boolean movementNecessary(World world, BlockPos pos) {
+	public static boolean movementNecessary(BlockState state, World world, BlockPos pos) {
-		BlockState state = world.getBlockState(pos);
 		if (isBrittle(state))
 			return true;
 		if (state.getBlock() instanceof FenceGateBlock)
@@ -68,18 +67,17 @@ public class BlockMovementTraits {
 		return true;
 	}
 
-	public static boolean movementAllowed(World world, BlockPos pos) {
+	public static boolean movementAllowed(BlockState state, World world, BlockPos pos) {
-		BlockState blockState = world.getBlockState(pos);
+		Block block = state.getBlock();
-		Block block = blockState.getBlock();
 		if (block instanceof AbstractChassisBlock)
 			return true;
-		if (blockState.getBlockHardness(world, pos) == -1)
+		if (state.getBlockHardness(world, pos) == -1)
 			return false;
-		if (AllBlockTags.NON_MOVABLE.matches(blockState))
+		if (AllBlockTags.NON_MOVABLE.matches(state))
 			return false;
 
 		// Move controllers only when they aren't moving
-		if (block instanceof MechanicalPistonBlock && blockState.get(MechanicalPistonBlock.STATE) != PistonState.MOVING)
+		if (block instanceof MechanicalPistonBlock && state.get(MechanicalPistonBlock.STATE) != PistonState.MOVING)
 			return true;
 		if (block instanceof MechanicalBearingBlock) {
 			TileEntity te = world.getTileEntity(pos);
@@ -97,11 +95,11 @@ public class BlockMovementTraits {
 				return !((PulleyTileEntity) te).running;
 		}
 
-		if (AllBlocks.BELT.has(blockState))
+		if (AllBlocks.BELT.has(state))
 			return true;
-		if (blockState.getBlock() instanceof GrindstoneBlock)
+		if (state.getBlock() instanceof GrindstoneBlock)
 			return true;
-		return blockState.getPushReaction() != PushReaction.BLOCK;
+		return state.getPushReaction() != PushReaction.BLOCK;
 	}
 
 	/**

src/main/java/com/simibubi/create/content/contraptions/components/structureMovement/Contraption.java

@@ -1,26 +1,5 @@
 package com.simibubi.create.content.contraptions.components.structureMovement;
 
-import static com.simibubi.create.content.contraptions.components.structureMovement.piston.MechanicalPistonBlock.isExtensionPole;
-import static com.simibubi.create.content.contraptions.components.structureMovement.piston.MechanicalPistonBlock.isPistonHead;
-
-import java.util.ArrayList;
-import java.util.Arrays;
-import java.util.HashMap;
-import java.util.HashSet;
-import java.util.Iterator;
-import java.util.List;
-import java.util.Map;
-import java.util.Optional;
-import java.util.Set;
-import java.util.UUID;
-import java.util.function.BiConsumer;
-import java.util.stream.Collectors;
-
-import javax.annotation.Nullable;
-
-import org.apache.commons.lang3.tuple.MutablePair;
-import org.apache.commons.lang3.tuple.Pair;
-
 import com.simibubi.create.AllBlocks;
 import com.simibubi.create.AllMovementBehaviours;
 import com.simibubi.create.content.contraptions.base.IRotate;
@@ -55,15 +34,7 @@ import com.simibubi.create.foundation.utility.NBTHelper;
 import com.simibubi.create.foundation.utility.NBTProcessors;
 import com.simibubi.create.foundation.utility.VecHelper;
 import com.simibubi.create.foundation.utility.worldWrappers.WrappedWorld;
-
+import net.minecraft.block.*;
-import net.minecraft.block.AbstractButtonBlock;
-import net.minecraft.block.Block;
-import net.minecraft.block.BlockState;
-import net.minecraft.block.Blocks;
-import net.minecraft.block.ChestBlock;
-import net.minecraft.block.DoorBlock;
-import net.minecraft.block.IWaterLoggable;
-import net.minecraft.block.PressurePlateBlock;
 import net.minecraft.block.material.PushReaction;
 import net.minecraft.entity.Entity;
 import net.minecraft.fluid.Fluids;
@@ -96,6 +67,16 @@ import net.minecraftforge.fluids.capability.IFluidHandler.FluidAction;
 import net.minecraftforge.fluids.capability.templates.FluidTank;
 import net.minecraftforge.items.IItemHandlerModifiable;
 import net.minecraftforge.items.wrapper.CombinedInvWrapper;
+import org.apache.commons.lang3.tuple.MutablePair;
+import org.apache.commons.lang3.tuple.Pair;
+
+import javax.annotation.Nullable;
+import java.util.*;
+import java.util.function.BiConsumer;
+import java.util.stream.Collectors;
+
+import static com.simibubi.create.content.contraptions.components.structureMovement.piston.MechanicalPistonBlock.isExtensionPole;
+import static com.simibubi.create.content.contraptions.components.structureMovement.piston.MechanicalPistonBlock.isPistonHead;
 
 public abstract class Contraption {
 
@@ -139,7 +120,7 @@ public abstract class Contraption {
 		stabilizedSubContraptions = new HashMap<>();
 	}
 
-	public abstract boolean assemble(World world, BlockPos pos);
+	public abstract boolean assemble(World world, BlockPos pos) throws AssemblyException;
 
 	public abstract boolean canBeStabilized(Direction facing, BlockPos localPos);
 
@@ -154,7 +135,7 @@ public abstract class Contraption {
 	}
 
 	protected boolean addToInitialFrontier(World world, BlockPos pos, Direction forcedDirection,
-		List<BlockPos> frontier) {
+		Queue<BlockPos> frontier) throws AssemblyException {
 		return true;
 	}
 
@@ -165,9 +146,9 @@ public abstract class Contraption {
 		return contraption;
 	}
 
-	public boolean searchMovedStructure(World world, BlockPos pos, @Nullable Direction forcedDirection) {
+	public boolean searchMovedStructure(World world, BlockPos pos, @Nullable Direction forcedDirection) throws AssemblyException {
 		initialPassengers.clear();
-		List<BlockPos> frontier = new ArrayList<>();
+		Queue<BlockPos> frontier = new LinkedList<>();
 		Set<BlockPos> visited = new HashSet<>();
 		anchor = pos;
 
@@ -181,10 +162,10 @@ public abstract class Contraption {
 		for (int limit = 100000; limit > 0; limit--) {
 			if (frontier.isEmpty())
 				return true;
-			if (!moveBlock(world, frontier.remove(0), forcedDirection, frontier, visited))
+			if (!moveBlock(world, forcedDirection, frontier, visited))
 				return false;
 		}
-		return false;
+		throw AssemblyException.structureTooLarge();
 	}
 
 	public void onEntityCreated(AbstractContraptionEntity entity) {
@@ -196,8 +177,12 @@ public abstract class Contraption {
 			StabilizedContraption subContraption = new StabilizedContraption(face);
 			World world = entity.world;
 			BlockPos pos = blockFace.getPos();
+			try {
 				if (!subContraption.assemble(world, pos))
 					continue;
+			} catch (AssemblyException e) {
+				continue;
+			}
 			subContraption.removeBlocksFromWorld(world, BlockPos.ZERO);
 			OrientedContraptionEntity movedContraption =
 				OrientedContraptionEntity.create(world, subContraption, Optional.of(face));
@@ -247,20 +232,25 @@ public abstract class Contraption {
 		fluidStorage.forEach((pos, mfs) -> mfs.tick(entity, pos, world.isRemote));
 	}
 
-	protected boolean moveBlock(World world, BlockPos pos, @Nullable Direction forcedDirection, List<BlockPos> frontier,
+	/** move the first block in frontier queue */
-		Set<BlockPos> visited) {
+	protected boolean moveBlock(World world, @Nullable Direction forcedDirection, Queue<BlockPos> frontier,
-		visited.add(pos);
+		Set<BlockPos> visited) throws AssemblyException {
-		frontier.remove(pos);
+		BlockPos pos = frontier.poll();
-
+		if (pos == null)
-		if (!world.isBlockPresent(pos))
 			return false;
+		visited.add(pos);
+
+		if (World.isOutsideBuildHeight(pos))
+			return true;
+		if (!world.isBlockPresent(pos))
+			throw AssemblyException.unloadedChunk(pos);
 		if (isAnchoringBlockAt(pos))
 			return true;
-		if (!BlockMovementTraits.movementNecessary(world, pos))
-			return true;
-		if (!movementAllowed(world, pos))
-			return false;
 		BlockState state = world.getBlockState(pos);
+		if (!BlockMovementTraits.movementNecessary(state, world, pos))
+			return true;
+		if (!movementAllowed(state, world, pos))
+			throw AssemblyException.unmovableBlock(pos, state);
 		if (state.getBlock() instanceof AbstractChassisBlock
 			&& !moveChassis(world, pos, forcedDirection, frontier, visited))
 			return false;
@@ -306,9 +296,10 @@ public abstract class Contraption {
 		}
 
 		// Cart assemblers attach themselves
-		BlockState stateBelow = world.getBlockState(pos.down());
+		BlockPos posDown = pos.down();
-		if (!visited.contains(pos.down()) && AllBlocks.CART_ASSEMBLER.has(stateBelow))
+		BlockState stateBelow = world.getBlockState(posDown);
-			frontier.add(pos.down());
+		if (!visited.contains(posDown) && AllBlocks.CART_ASSEMBLER.has(stateBelow))
+			frontier.add(posDown);
 
 		Map<Direction, SuperGlueEntity> superglue = SuperGlueHandler.gatherGlue(world, pos);
 
@@ -318,9 +309,9 @@ public abstract class Contraption {
 			BlockState blockState = world.getBlockState(offsetPos);
 			if (isAnchoringBlockAt(offsetPos))
 				continue;
-			if (!movementAllowed(world, offsetPos)) {
+			if (!movementAllowed(blockState, world, offsetPos)) {
 				if (offset == forcedDirection)
-					return false;
+					throw AssemblyException.unmovableBlock(pos, state);
 				continue;
 			}
 
@@ -349,10 +340,13 @@ public abstract class Contraption {
 		}
 
 		addBlock(pos, capture(world, pos));
-		return blocks.size() <= AllConfigs.SERVER.kinetics.maxBlocksMoved.get();
+		if (blocks.size() <= AllConfigs.SERVER.kinetics.maxBlocksMoved.get())
+			return true;
+		else
+			throw AssemblyException.structureTooLarge();
 	}
 
-	protected void movePistonHead(World world, BlockPos pos, List<BlockPos> frontier, Set<BlockPos> visited,
+	protected void movePistonHead(World world, BlockPos pos, Queue<BlockPos> frontier, Set<BlockPos> visited,
 		BlockState state) {
 		Direction direction = state.get(MechanicalPistonHeadBlock.FACING);
 		BlockPos offset = pos.offset(direction.getOpposite());
@@ -374,7 +368,7 @@ public abstract class Contraption {
 		}
 	}
 
-	protected void movePistonPole(World world, BlockPos pos, List<BlockPos> frontier, Set<BlockPos> visited,
+	protected void movePistonPole(World world, BlockPos pos, Queue<BlockPos> frontier, Set<BlockPos> visited,
 		BlockState state) {
 		for (Direction d : Iterate.directionsInAxis(state.get(PistonExtensionPoleBlock.FACING)
 			.getAxis())) {
@@ -397,7 +391,7 @@ public abstract class Contraption {
 		}
 	}
 
-	protected void moveGantryPinion(World world, BlockPos pos, List<BlockPos> frontier, Set<BlockPos> visited,
+	protected void moveGantryPinion(World world, BlockPos pos, Queue<BlockPos> frontier, Set<BlockPos> visited,
 		BlockState state) {
 		BlockPos offset = pos.offset(state.get(GantryPinionBlock.FACING));
 		if (!visited.contains(offset))
@@ -413,7 +407,7 @@ public abstract class Contraption {
 		}
 	}
 
-	protected void moveGantryShaft(World world, BlockPos pos, List<BlockPos> frontier, Set<BlockPos> visited,
+	protected void moveGantryShaft(World world, BlockPos pos, Queue<BlockPos> frontier, Set<BlockPos> visited,
 		BlockState state) {
 		for (Direction d : Iterate.directions) {
 			BlockPos offset = pos.offset(d);
@@ -429,7 +423,7 @@ public abstract class Contraption {
 		}
 	}
 
-	private void moveBearing(BlockPos pos, List<BlockPos> frontier, Set<BlockPos> visited, BlockState state) {
+	private void moveBearing(BlockPos pos, Queue<BlockPos> frontier, Set<BlockPos> visited, BlockState state) {
 		Direction facing = state.get(MechanicalBearingBlock.FACING);
 		if (!canBeStabilized(facing, pos.subtract(anchor))) {
 			BlockPos offset = pos.offset(facing);
@@ -440,7 +434,7 @@ public abstract class Contraption {
 		pendingSubContraptions.add(new BlockFace(pos, facing));
 	}
 
-	private void moveBelt(BlockPos pos, List<BlockPos> frontier, Set<BlockPos> visited, BlockState state) {
+	private void moveBelt(BlockPos pos, Queue<BlockPos> frontier, Set<BlockPos> visited, BlockState state) {
 		BlockPos nextPos = BeltBlock.nextSegmentPosition(state, pos, true);
 		BlockPos prevPos = BeltBlock.nextSegmentPosition(state, pos, false);
 		if (nextPos != null && !visited.contains(nextPos))
@@ -461,7 +455,7 @@ public abstract class Contraption {
 		}
 	}
 
-	private void movePulley(World world, BlockPos pos, List<BlockPos> frontier, Set<BlockPos> visited) {
+	private void movePulley(World world, BlockPos pos, Queue<BlockPos> frontier, Set<BlockPos> visited) {
 		int limit = AllConfigs.SERVER.kinetics.maxRopeLength.get();
 		BlockPos ropePos = pos;
 		while (limit-- >= 0) {
@@ -479,8 +473,8 @@ public abstract class Contraption {
 		}
 	}
 
-	private boolean moveMechanicalPiston(World world, BlockPos pos, List<BlockPos> frontier, Set<BlockPos> visited,
+	private boolean moveMechanicalPiston(World world, BlockPos pos, Queue<BlockPos> frontier, Set<BlockPos> visited, BlockState state) throws AssemblyException {
-		BlockState state) {
+		int limit = AllConfigs.SERVER.kinetics.maxPistonPoles.get();
 		Direction direction = state.get(MechanicalPistonBlock.FACING);
 		PistonState pistonState = state.get(MechanicalPistonBlock.STATE);
 		if (pistonState == PistonState.MOVING)
@@ -503,7 +497,7 @@ public abstract class Contraption {
 		return true;
 	}
 
-	private boolean moveChassis(World world, BlockPos pos, Direction movementDirection, List<BlockPos> frontier,
+	private boolean moveChassis(World world, BlockPos pos, Direction movementDirection, Queue<BlockPos> frontier,
 		Set<BlockPos> visited) {
 		TileEntity te = world.getTileEntity(pos);
 		if (!(te instanceof ChassisTileEntity))
@@ -588,8 +582,8 @@ public abstract class Contraption {
 		return globalPos.subtract(anchor);
 	}
 
-	protected boolean movementAllowed(World world, BlockPos pos) {
+	protected boolean movementAllowed(BlockState state, World world, BlockPos pos) {
-		return BlockMovementTraits.movementAllowed(world, pos);
+		return BlockMovementTraits.movementAllowed(state, world, pos);
 	}
 
 	protected boolean isAnchoringBlockAt(BlockPos pos) {

src/main/java/com/simibubi/create/content/contraptions/components/structureMovement/IDisplayAssemblyExceptions.java

@@ -0,0 +1,28 @@
+package com.simibubi.create.content.contraptions.components.structureMovement;
+
+import com.simibubi.create.content.contraptions.goggles.IHaveGoggleInformation;
+import com.simibubi.create.foundation.utility.Lang;
+import net.minecraft.util.text.TextFormatting;
+
+import java.util.Arrays;
+import java.util.List;
+
+public interface IDisplayAssemblyExceptions {
+
+	default boolean addExceptionToTooltip(List<String> tooltip) {
+		AssemblyException e = getLastAssemblyException();
+		if (e == null)
+			return false;
+
+		if (!tooltip.isEmpty())
+			tooltip.add("");
+
+		tooltip.add(IHaveGoggleInformation.spacing + TextFormatting.GOLD + Lang.translate("gui.assembly.exception"));
+		String text = e.getFormattedText();
+		Arrays.stream(text.split("\n")).forEach(l -> tooltip.add(IHaveGoggleInformation.spacing + TextFormatting.GRAY + l));
+
+		return true;
+	}
+
+	AssemblyException getLastAssemblyException();
+}

src/main/java/com/simibubi/create/content/contraptions/components/structureMovement/bearing/BearingContraption.java

@@ -4,6 +4,7 @@ import org.apache.commons.lang3.tuple.Pair;
 
 import com.simibubi.create.AllTags.AllBlockTags;
 import com.simibubi.create.content.contraptions.components.structureMovement.ContraptionType;
+import com.simibubi.create.content.contraptions.components.structureMovement.AssemblyException;
 import com.simibubi.create.content.contraptions.components.structureMovement.Contraption;
 
 import net.minecraft.nbt.CompoundNBT;
@@ -28,7 +29,7 @@ public class BearingContraption extends Contraption {
 	}
 
 	@Override
-	public boolean assemble(World world, BlockPos pos) {
+	public boolean assemble(World world, BlockPos pos) throws AssemblyException {
 		BlockPos offset = pos.offset(facing);
 		if (!searchMovedStructure(world, offset, null))
 			return false;

src/main/java/com/simibubi/create/content/contraptions/components/structureMovement/bearing/ClockworkBearingTileEntity.java

@@ -1,12 +1,10 @@
 package com.simibubi.create.content.contraptions.components.structureMovement.bearing;
 
-import java.util.List;
-
-import org.apache.commons.lang3.tuple.Pair;
-
 import com.simibubi.create.content.contraptions.base.KineticTileEntity;
 import com.simibubi.create.content.contraptions.components.structureMovement.AbstractContraptionEntity;
+import com.simibubi.create.content.contraptions.components.structureMovement.AssemblyException;
 import com.simibubi.create.content.contraptions.components.structureMovement.ControlledContraptionEntity;
+import com.simibubi.create.content.contraptions.components.structureMovement.IDisplayAssemblyExceptions;
 import com.simibubi.create.content.contraptions.components.structureMovement.bearing.ClockworkContraption.HandType;
 import com.simibubi.create.foundation.advancement.AllTriggers;
 import com.simibubi.create.foundation.gui.AllIcons;
@@ -16,7 +14,6 @@ import com.simibubi.create.foundation.tileEntity.behaviour.scrollvalue.ScrollOpt
 import com.simibubi.create.foundation.utility.AngleHelper;
 import com.simibubi.create.foundation.utility.Lang;
 import com.simibubi.create.foundation.utility.ServerSpeedProvider;
-
 import net.minecraft.block.BlockState;
 import net.minecraft.nbt.CompoundNBT;
 import net.minecraft.state.properties.BlockStateProperties;
@@ -25,8 +22,11 @@ import net.minecraft.util.Direction;
 import net.minecraft.util.Direction.Axis;
 import net.minecraft.util.math.BlockPos;
 import net.minecraft.util.math.MathHelper;
+import org.apache.commons.lang3.tuple.Pair;
 
-public class ClockworkBearingTileEntity extends KineticTileEntity implements IBearingTileEntity {
+import java.util.List;
+
+public class ClockworkBearingTileEntity extends KineticTileEntity implements IBearingTileEntity, IDisplayAssemblyExceptions {
 
 	protected ControlledContraptionEntity hourHand;
 	protected ControlledContraptionEntity minuteHand;
@@ -37,6 +37,7 @@ public class ClockworkBearingTileEntity extends KineticTileEntity implements IBe
 
 	protected boolean running;
 	protected boolean assembleNextTick;
+	protected AssemblyException lastException;
 
 	protected ScrollOptionBehaviour<ClockHands> operationMode;
 
@@ -105,6 +106,11 @@ public class ClockworkBearingTileEntity extends KineticTileEntity implements IBe
 		applyRotations();
 	}
 
+	@Override
+	public AssemblyException getLastAssemblyException() {
+		return lastException;
+	}
+
 	protected void applyRotations() {
 		BlockState blockState = getBlockState();
 		Axis axis = Axis.X;
@@ -199,8 +205,15 @@ public class ClockworkBearingTileEntity extends KineticTileEntity implements IBe
 		Direction direction = getBlockState().get(BlockStateProperties.FACING);
 
 		// Collect Construct
-		Pair<ClockworkContraption, ClockworkContraption> contraption =
+		Pair<ClockworkContraption, ClockworkContraption> contraption;
-			ClockworkContraption.assembleClockworkAt(world, pos, direction);
+		try {
+			contraption = ClockworkContraption.assembleClockworkAt(world, pos, direction);
+			lastException = null;
+		} catch (AssemblyException e) {
+			lastException = e;
+			sendData();
+			return;
+		}
 		if (contraption == null)
 			return;
 		if (contraption.getLeft() == null)
@@ -284,6 +297,7 @@ public class ClockworkBearingTileEntity extends KineticTileEntity implements IBe
 		compound.putBoolean("Running", running);
 		compound.putFloat("HourAngle", hourAngle);
 		compound.putFloat("MinuteAngle", minuteAngle);
+		AssemblyException.write(compound, lastException);
 		super.write(compound, clientPacket);
 	}
 
@@ -295,6 +309,7 @@ public class ClockworkBearingTileEntity extends KineticTileEntity implements IBe
 		running = compound.getBoolean("Running");
 		hourAngle = compound.getFloat("HourAngle");
 		minuteAngle = compound.getFloat("MinuteAngle");
+		lastException = AssemblyException.read(compound);
 		super.read(compound, clientPacket);
 
 		if (!clientPacket)

src/main/java/com/simibubi/create/content/contraptions/components/structureMovement/bearing/ClockworkContraption.java

@@ -7,13 +7,18 @@ import java.util.Set;
 import org.apache.commons.lang3.tuple.Pair;
 
 import com.simibubi.create.content.contraptions.components.structureMovement.ContraptionType;
+import com.simibubi.create.content.contraptions.components.structureMovement.AssemblyException;
 import com.simibubi.create.content.contraptions.components.structureMovement.Contraption;
 import com.simibubi.create.foundation.utility.NBTHelper;
-
 import net.minecraft.nbt.CompoundNBT;
 import net.minecraft.util.Direction;
 import net.minecraft.util.math.BlockPos;
 import net.minecraft.world.World;
+import org.apache.commons.lang3.tuple.Pair;
+
+import java.util.HashSet;
+import java.util.Queue;
+import java.util.Set;
 
 public class ClockworkContraption extends Contraption {
 
@@ -38,7 +43,7 @@ public class ClockworkContraption extends Contraption {
 	}
 
 	public static Pair<ClockworkContraption, ClockworkContraption> assembleClockworkAt(World world, BlockPos pos,
-		Direction direction) {
+		Direction direction) throws AssemblyException {
 		int hourArmBlocks = 0;
 
 		ClockworkContraption hourArm = new ClockworkContraption();
@@ -81,21 +86,23 @@ public class ClockworkContraption extends Contraption {
 	}
 	
 	@Override
-	public boolean assemble(World world, BlockPos pos) {
+	public boolean assemble(World world, BlockPos pos) throws AssemblyException {
 		return searchMovedStructure(world, pos, facing);
 	}
 
 	@Override
-	public boolean searchMovedStructure(World world, BlockPos pos, Direction direction) {
+	public boolean searchMovedStructure(World world, BlockPos pos, Direction direction) throws AssemblyException {
 		return super.searchMovedStructure(world, pos.offset(direction, offset + 1), null);
 	}
 
 	@Override
-	protected boolean moveBlock(World world, BlockPos pos, Direction direction, List<BlockPos> frontier,
+	protected boolean moveBlock(World world, Direction direction, Queue<BlockPos> frontier,
-		Set<BlockPos> visited) {
+		Set<BlockPos> visited) throws AssemblyException {
-		if (ignoreBlocks.contains(pos))
+		if (ignoreBlocks.contains(frontier.peek())) {
+			frontier.poll();
 			return true;
-		return super.moveBlock(world, pos, direction, frontier, visited);
+		}
+		return super.moveBlock(world, direction, frontier, visited);
 	}
 
 	@Override

src/main/java/com/simibubi/create/content/contraptions/components/structureMovement/bearing/MechanicalBearingTileEntity.java

@@ -1,12 +1,10 @@
 package com.simibubi.create.content.contraptions.components.structureMovement.bearing;
 
-import static net.minecraft.state.properties.BlockStateProperties.FACING;
-
-import java.util.List;
-
 import com.simibubi.create.content.contraptions.base.GeneratingKineticTileEntity;
 import com.simibubi.create.content.contraptions.components.structureMovement.AbstractContraptionEntity;
+import com.simibubi.create.content.contraptions.components.structureMovement.AssemblyException;
 import com.simibubi.create.content.contraptions.components.structureMovement.ControlledContraptionEntity;
+import com.simibubi.create.content.contraptions.components.structureMovement.IDisplayAssemblyExceptions;
 import com.simibubi.create.foundation.advancement.AllTriggers;
 import com.simibubi.create.foundation.item.TooltipHelper;
 import com.simibubi.create.foundation.tileEntity.TileEntityBehaviour;
@@ -14,7 +12,6 @@ import com.simibubi.create.foundation.tileEntity.behaviour.scrollvalue.ScrollOpt
 import com.simibubi.create.foundation.utility.AngleHelper;
 import com.simibubi.create.foundation.utility.Lang;
 import com.simibubi.create.foundation.utility.ServerSpeedProvider;
-
 import net.minecraft.block.BlockState;
 import net.minecraft.nbt.CompoundNBT;
 import net.minecraft.state.properties.BlockStateProperties;
@@ -23,7 +20,11 @@ import net.minecraft.util.Direction;
 import net.minecraft.util.math.BlockPos;
 import net.minecraft.util.math.MathHelper;
 
-public class MechanicalBearingTileEntity extends GeneratingKineticTileEntity implements IBearingTileEntity {
+import java.util.List;
+
+import static net.minecraft.state.properties.BlockStateProperties.FACING;
+
+public class MechanicalBearingTileEntity extends GeneratingKineticTileEntity implements IBearingTileEntity, IDisplayAssemblyExceptions {
 
 	protected ScrollOptionBehaviour<RotationMode> movementMode;
 	protected ControlledContraptionEntity movedContraption;
@@ -31,6 +32,7 @@ public class MechanicalBearingTileEntity extends GeneratingKineticTileEntity imp
 	protected boolean running;
 	protected boolean assembleNextTick;
 	protected float clientAngleDiff;
+	protected AssemblyException lastException;
 
 	public MechanicalBearingTileEntity(TileEntityType<? extends MechanicalBearingTileEntity> type) {
 		super(type);
@@ -62,6 +64,7 @@ public class MechanicalBearingTileEntity extends GeneratingKineticTileEntity imp
 	public void write(CompoundNBT compound, boolean clientPacket) {
 		compound.putBoolean("Running", running);
 		compound.putFloat("Angle", angle);
+		AssemblyException.write(compound, lastException);
 		super.write(compound, clientPacket);
 	}
 
@@ -70,6 +73,7 @@ public class MechanicalBearingTileEntity extends GeneratingKineticTileEntity imp
 		float angleBefore = angle;
 		running = compound.getBoolean("Running");
 		angle = compound.getFloat("Angle");
+		lastException = AssemblyException.read(compound);
 		super.read(compound, clientPacket);
 		if (!clientPacket)
 			return;
@@ -104,6 +108,11 @@ public class MechanicalBearingTileEntity extends GeneratingKineticTileEntity imp
 		return speed;
 	}
 
+	@Override
+	public AssemblyException getLastAssemblyException() {
+		return lastException;
+	}
+
 	protected boolean isWindmill() {
 		return false;
 	}
@@ -120,9 +129,17 @@ public class MechanicalBearingTileEntity extends GeneratingKineticTileEntity imp
 
 		Direction direction = getBlockState().get(FACING);
 		BearingContraption contraption = new BearingContraption(isWindmill(), direction);
+		try {
 			if (!contraption.assemble(world, pos))
 				return;
 
+			lastException = null;
+		} catch (AssemblyException e) {
+			lastException = e;
+			sendData();
+			return;
+		}
+
 		if (isWindmill())
 			AllTriggers.triggerForNearbyPlayers(AllTriggers.WINDMILL, world, pos, 5);
 		if (contraption.getSailBlocks() >= 16 * 8)
@@ -281,5 +298,4 @@ public class MechanicalBearingTileEntity extends GeneratingKineticTileEntity imp
 		TooltipHelper.addHint(tooltip, "hint.empty_bearing");
 		return true;
 	}
-
 }

src/main/java/com/simibubi/create/content/contraptions/components/structureMovement/bearing/SailBlock.java

@@ -64,16 +64,9 @@ public class SailBlock extends ProperDirectionalBlock {
 	public ActionResultType onUse(BlockState state, World world, BlockPos pos, PlayerEntity player, Hand hand, BlockRayTraceResult ray) {
 		ItemStack heldItem = player.getHeldItem(hand);
 
-		if (AllBlocks.SAIL.isIn(heldItem) || AllBlocks.SAIL_FRAME.isIn(heldItem)) {
 		IPlacementHelper placementHelper = PlacementHelpers.get(placementHelperId);
-			PlacementOffset offset = placementHelper.getOffset(world, state, pos, ray);
+		if (placementHelper.matchesItem(heldItem))
-
+			return placementHelper.getOffset(world, state, pos, ray).placeInWorld(world, (BlockItem) heldItem.getItem(), player, hand, ray);
-			if (!offset.isReplaceable(world))
-				return ActionResultType.PASS;
-
-			offset.placeInWorld(world, ((BlockItem) heldItem.getItem()).getBlock().getDefaultState(), player, heldItem);
-			return ActionResultType.SUCCESS;
-		}
 
 		if (heldItem.getItem() instanceof ShearsItem) {
 			if (!world.isRemote)

src/main/java/com/simibubi/create/content/contraptions/components/structureMovement/bearing/StabilizedContraption.java

@@ -1,6 +1,7 @@
 package com.simibubi.create.content.contraptions.components.structureMovement.bearing;
 
 import com.simibubi.create.content.contraptions.components.structureMovement.ContraptionType;
+import com.simibubi.create.content.contraptions.components.structureMovement.AssemblyException;
 import com.simibubi.create.content.contraptions.components.structureMovement.Contraption;
 
 import net.minecraft.nbt.CompoundNBT;
@@ -20,7 +21,7 @@ public class StabilizedContraption extends Contraption {
 	}
 
 	@Override
-	public boolean assemble(World world, BlockPos pos) {
+	public boolean assemble(World world, BlockPos pos) throws AssemblyException {
 		BlockPos offset = pos.offset(facing);
 		if (!searchMovedStructure(world, offset, null))
 			return false;

src/main/java/com/simibubi/create/content/contraptions/components/structureMovement/chassis/ChassisTileEntity.java

@@ -7,6 +7,7 @@ import java.util.Collections;
 import java.util.HashSet;
 import java.util.LinkedList;
 import java.util.List;
+import java.util.Queue;
 import java.util.Set;
 
 import com.simibubi.create.AllBlocks;
@@ -76,12 +77,12 @@ public class ChassisTileEntity extends SmartTileEntity {
 	}
 
 	public List<ChassisTileEntity> collectChassisGroup() {
-		List<BlockPos> frontier = new ArrayList<>();
+		Queue<BlockPos> frontier = new LinkedList<>();
 		List<ChassisTileEntity> collected = new ArrayList<>();
 		Set<BlockPos> visited = new HashSet<>();
 		frontier.add(pos);
 		while (!frontier.isEmpty()) {
-			BlockPos current = frontier.remove(0);
+			BlockPos current = frontier.poll();
 			if (visited.contains(current))
 				continue;
 			visited.add(current);
@@ -96,7 +97,7 @@ public class ChassisTileEntity extends SmartTileEntity {
 		return collected;
 	}
 
-	public boolean addAttachedChasses(List<BlockPos> frontier, Set<BlockPos> visited) {
+	public boolean addAttachedChasses(Queue<BlockPos> frontier, Set<BlockPos> visited) {
 		BlockState state = getBlockState();
 		if (!(state.getBlock() instanceof AbstractChassisBlock))
 			return false;
@@ -166,7 +167,7 @@ public class ChassisTileEntity extends SmartTileEntity {
 					break;
 
 				// Ignore replaceable Blocks and Air-like
-				if (!BlockMovementTraits.movementNecessary(world, current))
+				if (!BlockMovementTraits.movementNecessary(currentState, world, current))
 					break;
 				if (BlockMovementTraits.isBrittle(currentState))
 					break;
@@ -207,7 +208,7 @@ public class ChassisTileEntity extends SmartTileEntity {
 					continue;
 				if (!searchPos.withinDistance(pos, chassisRange + .5f))
 					continue;
-				if (!BlockMovementTraits.movementNecessary(world, searchPos))
+				if (!BlockMovementTraits.movementNecessary(searchedState, world, searchPos))
 					continue;
 				if (BlockMovementTraits.isBrittle(searchedState))
 					continue;

src/main/java/com/simibubi/create/content/contraptions/components/structureMovement/gantry/GantryContraption.java

@@ -1,9 +1,9 @@
 package com.simibubi.create.content.contraptions.components.structureMovement.gantry;
 
 import com.simibubi.create.AllBlocks;
+import com.simibubi.create.content.contraptions.components.structureMovement.AssemblyException;
 import com.simibubi.create.content.contraptions.components.structureMovement.ContraptionType;
 import com.simibubi.create.content.contraptions.components.structureMovement.TranslatingContraption;
-
 import net.minecraft.nbt.CompoundNBT;
 import net.minecraft.util.Direction;
 import net.minecraft.util.math.BlockPos;
@@ -21,7 +21,7 @@ public class GantryContraption extends TranslatingContraption {
 	}
 
 	@Override
-	public boolean assemble(World world, BlockPos pos) {
+	public boolean assemble(World world, BlockPos pos) throws AssemblyException {
 		if (!searchMovedStructure(world, pos, null))
 			return false;
 		startMoving(world);

src/main/java/com/simibubi/create/content/contraptions/components/structureMovement/gantry/GantryPinionTileEntity.java

@@ -1,23 +1,26 @@
 package com.simibubi.create.content.contraptions.components.structureMovement.gantry;
 
-import static net.minecraft.state.properties.BlockStateProperties.FACING;
-
 import com.simibubi.create.AllBlocks;
 import com.simibubi.create.content.contraptions.base.KineticTileEntity;
+import com.simibubi.create.content.contraptions.components.structureMovement.AssemblyException;
 import com.simibubi.create.content.contraptions.components.structureMovement.ContraptionCollider;
+import com.simibubi.create.content.contraptions.components.structureMovement.IDisplayAssemblyExceptions;
 import com.simibubi.create.content.contraptions.relays.advanced.GantryShaftBlock;
 import com.simibubi.create.content.contraptions.relays.advanced.GantryShaftTileEntity;
-
 import net.minecraft.block.BlockState;
+import net.minecraft.nbt.CompoundNBT;
 import net.minecraft.tileentity.TileEntity;
 import net.minecraft.tileentity.TileEntityType;
 import net.minecraft.util.Direction;
 import net.minecraft.util.Direction.Axis;
 import net.minecraft.util.math.BlockPos;
 
-public class GantryPinionTileEntity extends KineticTileEntity {
+import static net.minecraft.state.properties.BlockStateProperties.FACING;
+
+public class GantryPinionTileEntity extends KineticTileEntity implements IDisplayAssemblyExceptions {
 
 	boolean assembleNextTick;
+	protected AssemblyException lastException;
 
 	public GantryPinionTileEntity(TileEntityType<?> typeIn) {
 		super(typeIn);
@@ -50,6 +53,11 @@ public class GantryPinionTileEntity extends KineticTileEntity {
 		}
 	}
 
+	@Override
+	public AssemblyException getLastAssemblyException() {
+		return lastException;
+	}
+
 	private void tryAssemble() {
 		BlockState blockState = getBlockState();
 		if (!(blockState.getBlock() instanceof GantryPinionBlock))
@@ -71,8 +79,17 @@ public class GantryPinionTileEntity extends KineticTileEntity {
 		if (pinionMovementSpeed < 0)
 			movementDirection = movementDirection.getOpposite();
 
+		try {
+			lastException = null;
 			if (!contraption.assemble(world, pos))
 				return;
+
+			sendData();
+		} catch (AssemblyException e) {
+			lastException = e;
+			sendData();
+			return;
+		}
 		if (ContraptionCollider.isCollidingWithWorld(world, contraption, pos.offset(movementDirection),
 			movementDirection))
 			return;
@@ -85,6 +102,18 @@ public class GantryPinionTileEntity extends KineticTileEntity {
 		world.addEntity(movedContraption);
 	}
 
+	@Override
+	protected void write(CompoundNBT compound, boolean clientPacket) {
+		AssemblyException.write(compound, lastException);
+		super.write(compound, clientPacket);
+	}
+
+	@Override
+	protected void read(CompoundNBT compound, boolean clientPacket) {
+		lastException = AssemblyException.read(compound);
+		super.read(compound, clientPacket);
+	}
+
 	@Override
 	public float propagateRotationTo(KineticTileEntity target, BlockState stateFrom, BlockState stateTo, BlockPos diff,
 		boolean connectedViaAxes, boolean connectedViaCogs) {

src/main/java/com/simibubi/create/content/contraptions/components/structureMovement/glue/SuperGlueEntity.java

@@ -180,7 +180,7 @@ public class SuperGlueEntity extends Entity implements IEntityAdditionalSpawnDat
 		BlockState state = world.getBlockState(pos);
 		if (BlockMovementTraits.isBlockAttachedTowards(world, pos, state, direction))
 			return true;
-		if (!BlockMovementTraits.movementNecessary(world, pos))
+		if (!BlockMovementTraits.movementNecessary(state, world, pos))
 			return false;
 		if (BlockMovementTraits.notSupportive(state, direction))
 			return false;

src/main/java/com/simibubi/create/content/contraptions/components/structureMovement/glue/SuperGlueHandler.java

@@ -1,13 +1,9 @@
 package com.simibubi.create.content.contraptions.components.structureMovement.glue;
 
-import java.util.HashMap;
-import java.util.List;
-import java.util.Map;
-
 import com.simibubi.create.AllItems;
 import com.simibubi.create.foundation.networking.AllPackets;
+import com.simibubi.create.foundation.utility.placement.IPlacementHelper;
 import com.simibubi.create.foundation.utility.worldWrappers.RayTraceWorld;
-
 import net.minecraft.block.Blocks;
 import net.minecraft.entity.Entity;
 import net.minecraft.entity.EntityType;
@@ -15,12 +11,8 @@ import net.minecraft.entity.player.PlayerEntity;
 import net.minecraft.item.ItemStack;
 import net.minecraft.nbt.CompoundNBT;
 import net.minecraft.util.Direction;
-import net.minecraft.util.math.AxisAlignedBB;
+import net.minecraft.util.math.*;
-import net.minecraft.util.math.BlockPos;
-import net.minecraft.util.math.BlockRayTraceResult;
-import net.minecraft.util.math.RayTraceContext;
 import net.minecraft.util.math.RayTraceResult.Type;
-import net.minecraft.util.math.Vec3d;
 import net.minecraft.world.IWorld;
 import net.minecraft.world.World;
 import net.minecraftforge.event.world.BlockEvent.EntityPlaceEvent;
@@ -28,6 +20,10 @@ import net.minecraftforge.eventbus.api.SubscribeEvent;
 import net.minecraftforge.fml.common.Mod.EventBusSubscriber;
 import net.minecraftforge.fml.network.PacketDistributor;
 
+import java.util.HashMap;
+import java.util.List;
+import java.util.Map;
+
 @EventBusSubscriber
 public class SuperGlueHandler {
 
@@ -65,6 +61,8 @@ public class SuperGlueHandler {
 			return;
 		if (AllItems.WRENCH.isIn(placer.getHeldItemMainhand()))
 			return;
+		if (event.getPlacedAgainst() == IPlacementHelper.ID)
+			return;
 
 		double distance = placer.getAttribute(PlayerEntity.REACH_DISTANCE)
 			.getValue();

src/main/java/com/simibubi/create/content/contraptions/components/structureMovement/mounted/CartAssemblerBlock.java

@@ -3,6 +3,7 @@ package com.simibubi.create.content.contraptions.components.structureMovement.mo
 import com.simibubi.create.AllBlocks;
 import com.simibubi.create.AllShapes;
 import com.simibubi.create.AllTileEntities;
+import com.simibubi.create.content.contraptions.components.structureMovement.AssemblyException;
 import com.simibubi.create.content.contraptions.components.structureMovement.OrientedContraptionEntity;
 import com.simibubi.create.content.contraptions.components.structureMovement.mounted.CartAssemblerTileEntity.CartMovementMode;
 import com.simibubi.create.content.contraptions.components.structureMovement.train.CouplingHandler;
@@ -229,14 +230,28 @@ public class CartAssemblerBlock extends AbstractRailBlock
 			.isCoupledThroughContraption())
 			return;
 
-		CartMovementMode mode =
+		
-			getTileEntityOptional(world, pos).map(te -> CartMovementMode.values()[te.movementMode.value])
+		Optional<CartAssemblerTileEntity> assembler = getTileEntityOptional(world, pos);
+		CartMovementMode mode = assembler.map(te -> CartMovementMode.values()[te.movementMode.value])
 				.orElse(CartMovementMode.ROTATE);
 
 		MountedContraption contraption = new MountedContraption(mode);
+		try {
 			if (!contraption.assemble(world, pos))
 				return;
 
+			assembler.ifPresent(te -> {
+				te.lastException = null;
+				te.sendData();
+			});
+		} catch (AssemblyException e) {
+			assembler.ifPresent(te -> {
+				te.lastException = e;
+				te.sendData();
+			});
+			return;
+		}
+
 		boolean couplingFound = contraption.connectedCart != null;
 		Optional<Direction> initialOrientation = cart.getMotion()
 			.length() < 1 / 512f ? Optional.empty() : Optional.of(cart.getAdjustedHorizontalFacing());

src/main/java/com/simibubi/create/content/contraptions/components/structureMovement/mounted/CartAssemblerTileEntity.java

@@ -1,7 +1,7 @@
 package com.simibubi.create.content.contraptions.components.structureMovement.mounted;
 
-import java.util.List;
+import com.simibubi.create.content.contraptions.components.structureMovement.AssemblyException;
-
+import com.simibubi.create.content.contraptions.components.structureMovement.IDisplayAssemblyExceptions;
 import com.simibubi.create.foundation.gui.AllIcons;
 import com.simibubi.create.foundation.tileEntity.SmartTileEntity;
 import com.simibubi.create.foundation.tileEntity.TileEntityBehaviour;
@@ -11,17 +11,20 @@ import com.simibubi.create.foundation.tileEntity.behaviour.scrollvalue.INamedIco
 import com.simibubi.create.foundation.tileEntity.behaviour.scrollvalue.ScrollOptionBehaviour;
 import com.simibubi.create.foundation.utility.Lang;
 import com.simibubi.create.foundation.utility.VecHelper;
-
+import net.minecraft.nbt.CompoundNBT;
 import net.minecraft.state.properties.RailShape;
 import net.minecraft.tileentity.TileEntityType;
 import net.minecraft.util.Direction.Axis;
 import net.minecraft.util.math.Vec3d;
 
-public class CartAssemblerTileEntity extends SmartTileEntity {
+import java.util.List;
+
+public class CartAssemblerTileEntity extends SmartTileEntity implements IDisplayAssemblyExceptions {
 	private static final int assemblyCooldown = 8;
 
 	protected ScrollOptionBehaviour<CartMovementMode> movementMode;
 	private int ticksSinceMinecartUpdate;
+	protected AssemblyException lastException;
 
 	public CartAssemblerTileEntity(TileEntityType<? extends CartAssemblerTileEntity> type) {
 		super(type);
@@ -44,6 +47,23 @@ public class CartAssemblerTileEntity extends SmartTileEntity {
 		behaviours.add(movementMode);
 	}
 
+	@Override
+	public void write(CompoundNBT compound, boolean clientPacket) {
+		AssemblyException.write(compound, lastException);
+		super.write(compound, clientPacket);
+	}
+
+	@Override
+	protected void read(CompoundNBT compound, boolean clientPacket) {
+		lastException = AssemblyException.read(compound);
+		super.read(compound, clientPacket);
+	}
+
+	@Override
+	public AssemblyException getLastAssemblyException() {
+		return lastException;
+	}
+
 	protected ValueBoxTransform getMovementModeSlot() {
 		return new CartAssemblerValueBoxTransform();
 	}
@@ -103,5 +123,4 @@ public class CartAssemblerTileEntity extends SmartTileEntity {
 	public boolean isMinecartUpdateValid() {
 		return ticksSinceMinecartUpdate >= assemblyCooldown;
 	}
-
 }

src/main/java/com/simibubi/create/content/contraptions/components/structureMovement/mounted/MountedContraption.java

@@ -2,12 +2,13 @@ package com.simibubi.create.content.contraptions.components.structureMovement.mo
 
 import static com.simibubi.create.content.contraptions.components.structureMovement.mounted.CartAssemblerBlock.RAIL_SHAPE;
 
-import java.util.List;
+import java.util.Queue;
 
 import org.apache.commons.lang3.tuple.Pair;
 
 import com.simibubi.create.AllBlocks;
 import com.simibubi.create.content.contraptions.components.structureMovement.ContraptionType;
+import com.simibubi.create.content.contraptions.components.structureMovement.AssemblyException;
 import com.simibubi.create.content.contraptions.components.structureMovement.Contraption;
 import com.simibubi.create.content.contraptions.components.structureMovement.mounted.CartAssemblerTileEntity.CartMovementMode;
 import com.simibubi.create.foundation.utility.Iterate;
@@ -52,7 +53,7 @@ public class MountedContraption extends Contraption {
 	}
 	
 	@Override
-	public boolean assemble(World world, BlockPos pos) {
+	public boolean assemble(World world, BlockPos pos) throws AssemblyException {
 		BlockState state = world.getBlockState(pos);
 		if (!state.has(RAIL_SHAPE))
 			return false;
@@ -70,7 +71,7 @@ public class MountedContraption extends Contraption {
 	}
 	
 	@Override
-	protected boolean addToInitialFrontier(World world, BlockPos pos, Direction direction, List<BlockPos> frontier) {
+	protected boolean addToInitialFrontier(World world, BlockPos pos, Direction direction, Queue<BlockPos> frontier) {
 		frontier.clear();
 		frontier.add(pos.up());
 		return true;
@@ -104,11 +105,10 @@ public class MountedContraption extends Contraption {
 	}
 
 	@Override
-	protected boolean movementAllowed(World world, BlockPos pos) {
+	protected boolean movementAllowed(BlockState state, World world, BlockPos pos) {
-		BlockState blockState = world.getBlockState(pos);
+		if (!pos.equals(anchor) && AllBlocks.CART_ASSEMBLER.has(state))
-		if (!pos.equals(anchor) && AllBlocks.CART_ASSEMBLER.has(blockState))
+			return testSecondaryCartAssembler(world, state, pos);
-			return testSecondaryCartAssembler(world, blockState, pos);
+		return super.movementAllowed(state, world, pos);
-		return super.movementAllowed(world, pos);
 	}
 
 	protected boolean testSecondaryCartAssembler(World world, BlockState state, BlockPos pos) {

src/main/java/com/simibubi/create/content/contraptions/components/structureMovement/piston/LinearActuatorTileEntity.java

@@ -1,24 +1,21 @@
 package com.simibubi.create.content.contraptions.components.structureMovement.piston;
 
-import java.util.List;
-
 import com.simibubi.create.content.contraptions.base.KineticTileEntity;
-import com.simibubi.create.content.contraptions.components.structureMovement.AbstractContraptionEntity;
+import com.simibubi.create.content.contraptions.components.structureMovement.*;
-import com.simibubi.create.content.contraptions.components.structureMovement.ControlledContraptionEntity;
-import com.simibubi.create.content.contraptions.components.structureMovement.IControlContraption;
 import com.simibubi.create.foundation.tileEntity.TileEntityBehaviour;
 import com.simibubi.create.foundation.tileEntity.behaviour.ValueBoxTransform;
 import com.simibubi.create.foundation.tileEntity.behaviour.scrollvalue.ScrollOptionBehaviour;
 import com.simibubi.create.foundation.utility.Lang;
 import com.simibubi.create.foundation.utility.ServerSpeedProvider;
-
 import net.minecraft.nbt.CompoundNBT;
 import net.minecraft.tileentity.TileEntityType;
 import net.minecraft.util.math.BlockPos;
 import net.minecraft.util.math.MathHelper;
 import net.minecraft.util.math.Vec3d;
 
-public abstract class LinearActuatorTileEntity extends KineticTileEntity implements IControlContraption {
+import java.util.List;
+
+public abstract class LinearActuatorTileEntity extends KineticTileEntity implements IControlContraption, IDisplayAssemblyExceptions {
 
 	public float offset;
 	public boolean running;
@@ -27,6 +24,7 @@ public abstract class LinearActuatorTileEntity extends KineticTileEntity impleme
 	protected boolean forceMove;
 	protected ScrollOptionBehaviour<MovementMode> movementMode;
 	protected boolean waitingForSpeedChange;
+	protected AssemblyException lastException;
 
 	// Custom position sync
 	protected float clientOffsetDiff;
@@ -80,7 +78,13 @@ public abstract class LinearActuatorTileEntity extends KineticTileEntity impleme
 				return;
 			} else {
 				if (getSpeed() != 0)
+					try {
 						assemble();
+						lastException = null;
+					} catch (AssemblyException e) {
+						lastException = e;
+					}
+				sendData();
 			}
 			return;
 		}
@@ -153,6 +157,7 @@ public abstract class LinearActuatorTileEntity extends KineticTileEntity impleme
 		compound.putBoolean("Running", running);
 		compound.putBoolean("Waiting", waitingForSpeedChange);
 		compound.putFloat("Offset", offset);
+		AssemblyException.write(compound, lastException);
 		super.write(compound, clientPacket);
 
 		if (clientPacket && forceMove) {
@@ -169,6 +174,7 @@ public abstract class LinearActuatorTileEntity extends KineticTileEntity impleme
 		running = compound.getBoolean("Running");
 		waitingForSpeedChange = compound.getBoolean("Waiting");
 		offset = compound.getFloat("Offset");
+		lastException = AssemblyException.read(compound);
 		super.read(compound, clientPacket);
 
 		if (!clientPacket)
@@ -183,9 +189,14 @@ public abstract class LinearActuatorTileEntity extends KineticTileEntity impleme
 			movedContraption = null;
 	}
 
+	@Override
+	public AssemblyException getLastAssemblyException() {
+		return lastException;
+	}
+
 	public abstract void disassemble();
 
-	protected abstract void assemble();
+	protected abstract void assemble() throws AssemblyException;
 
 	protected abstract int getExtensionRange();
 
@@ -288,5 +299,4 @@ public abstract class LinearActuatorTileEntity extends KineticTileEntity impleme
 	public BlockPos getBlockPosition() {
 		return pos;
 	}
-
 }

src/main/java/com/simibubi/create/content/contraptions/components/structureMovement/piston/MechanicalPistonTileEntity.java

@@ -2,6 +2,7 @@ package com.simibubi.create.content.contraptions.components.structureMovement.pi
 
 import com.simibubi.create.AllBlocks;
 import com.simibubi.create.content.contraptions.base.IRotate;
+import com.simibubi.create.content.contraptions.components.structureMovement.AssemblyException;
 import com.simibubi.create.content.contraptions.components.structureMovement.ContraptionCollider;
 import com.simibubi.create.content.contraptions.components.structureMovement.ControlledContraptionEntity;
 import com.simibubi.create.content.contraptions.components.structureMovement.DirectionalExtenderScrollOptionSlot;
@@ -41,7 +42,7 @@ public class MechanicalPistonTileEntity extends LinearActuatorTileEntity {
 	}
 
 	@Override
-	public void assemble() {
+	public void assemble() throws AssemblyException {
 		if (!(world.getBlockState(pos)
 			.getBlock() instanceof MechanicalPistonBlock))
 			return;

src/main/java/com/simibubi/create/content/contraptions/components/structureMovement/piston/PistonContraption.java

@@ -1,7 +1,8 @@
 package com.simibubi.create.content.contraptions.components.structureMovement.piston;
 
-import com.simibubi.create.content.contraptions.components.structureMovement.ContraptionType;
+import com.simibubi.create.content.contraptions.components.structureMovement.AssemblyException;
 import com.simibubi.create.content.contraptions.components.structureMovement.BlockMovementTraits;
+import com.simibubi.create.content.contraptions.components.structureMovement.ContraptionType;
 import com.simibubi.create.content.contraptions.components.structureMovement.TranslatingContraption;
 import com.simibubi.create.content.contraptions.components.structureMovement.piston.MechanicalPistonBlock.*;
 import com.simibubi.create.foundation.config.AllConfigs;
@@ -23,6 +24,7 @@ import org.apache.commons.lang3.tuple.Pair;
 
 import java.util.ArrayList;
 import java.util.List;
+import java.util.Queue;
 
 import static com.simibubi.create.AllBlocks.MECHANICAL_PISTON_HEAD;
 import static com.simibubi.create.AllBlocks.PISTON_EXTENSION_POLE;
@@ -51,7 +53,7 @@ public class PistonContraption extends TranslatingContraption {
 	}
 
 	@Override
-	public boolean assemble(World world, BlockPos pos) {
+	public boolean assemble(World world, BlockPos pos) throws AssemblyException {
 		if (!collectExtensions(world, pos, orientation))
 			return false;
 		int count = blocks.size();
@@ -66,7 +68,7 @@ public class PistonContraption extends TranslatingContraption {
 		return true;
 	}
 
-	private boolean collectExtensions(World world, BlockPos pos, Direction direction) {
+	private boolean collectExtensions(World world, BlockPos pos, Direction direction) throws AssemblyException {
 		List<BlockInfo> poles = new ArrayList<>();
 		BlockPos actualStart = pos;
 		BlockState nextBlock = world.getBlockState(actualStart.offset(direction));
@@ -89,7 +91,7 @@ public class PistonContraption extends TranslatingContraption {
 
 				nextBlock = world.getBlockState(actualStart.offset(direction));
 				if (extensionsInFront > MechanicalPistonBlock.maxAllowedPistonPoles())
-					return false;
+					throw AssemblyException.tooManyPistonPoles();
 			}
 		}
 
@@ -112,7 +114,7 @@ public class PistonContraption extends TranslatingContraption {
 			nextBlock = world.getBlockState(end.offset(direction.getOpposite()));
 
 			if (extensionsInFront + extensionsInBack > MechanicalPistonBlock.maxAllowedPistonPoles())
-				return false;
+				throw AssemblyException.tooManyPistonPoles();
 		}
 
 		anchor = pos.offset(direction, initialExtensionProgress + 1);
@@ -124,7 +126,7 @@ public class PistonContraption extends TranslatingContraption {
 						1, 1);
 
 		if (extensionLength == 0)
-			return false;
+			throw AssemblyException.noPistonPoles();
 
 		bounds = new AxisAlignedBB(0, 0, 0, 0, 0, 0);
 
@@ -144,7 +146,7 @@ public class PistonContraption extends TranslatingContraption {
 	}
 
 	@Override
-	protected boolean addToInitialFrontier(World world, BlockPos pos, Direction direction, List<BlockPos> frontier) {
+	protected boolean addToInitialFrontier(World world, BlockPos pos, Direction direction, Queue<BlockPos> frontier) throws AssemblyException {
 		frontier.clear();
 		boolean sticky = isStickyPiston(world.getBlockState(pos.offset(orientation, -1)));
 		boolean retracting = direction != orientation;
@@ -154,17 +156,22 @@ public class PistonContraption extends TranslatingContraption {
 			if (offset == 1 && retracting)
 				return true;
 			BlockPos currentPos = pos.offset(orientation, offset + initialExtensionProgress);
-			if (!world.isBlockPresent(currentPos))
+			if (retracting && World.isOutsideBuildHeight(currentPos))
-				return false;
-			if (!BlockMovementTraits.movementNecessary(world, currentPos))
 				return true;
+			if (!world.isBlockPresent(currentPos))
+				throw AssemblyException.unloadedChunk(currentPos);
 			BlockState state = world.getBlockState(currentPos);
+			if (!BlockMovementTraits.movementNecessary(state, world, currentPos))
+				return true;
 			if (BlockMovementTraits.isBrittle(state) && !(state.getBlock() instanceof CarpetBlock))
 				return true;
 			if (isPistonHead(state) && state.get(FACING) == direction.getOpposite())
 				return true;
-			if (!BlockMovementTraits.movementAllowed(world, currentPos))
+			if (!BlockMovementTraits.movementAllowed(state, world, currentPos))
-				return retracting;
+				if (retracting)
+					return true;
+				else
+					throw AssemblyException.unmovableBlock(currentPos, state);
 			if (retracting && state.getPushReaction() == PushReaction.PUSH_ONLY)
 				return true;
 			frontier.add(currentPos);

src/main/java/com/simibubi/create/content/contraptions/components/structureMovement/piston/PistonExtensionPoleBlock.java

@@ -7,7 +7,6 @@ import com.simibubi.create.content.contraptions.wrench.IWrenchable;
 import com.simibubi.create.foundation.block.ProperDirectionalBlock;
 import com.simibubi.create.foundation.utility.placement.IPlacementHelper;
 import com.simibubi.create.foundation.utility.placement.PlacementHelpers;
-import com.simibubi.create.foundation.utility.placement.PlacementOffset;
 import com.simibubi.create.foundation.utility.placement.util.PoleHelper;
 import mcp.MethodsReturnNonnullByDefault;
 import net.minecraft.block.Block;
@@ -17,6 +16,7 @@ import net.minecraft.block.material.PushReaction;
 import net.minecraft.entity.player.PlayerEntity;
 import net.minecraft.fluid.Fluids;
 import net.minecraft.fluid.IFluidState;
+import net.minecraft.item.BlockItem;
 import net.minecraft.item.BlockItemUseContext;
 import net.minecraft.item.ItemStack;
 import net.minecraft.state.StateContainer.Builder;
@@ -114,26 +114,9 @@ public class PistonExtensionPoleBlock extends ProperDirectionalBlock implements
     public ActionResultType onUse(BlockState state, World world, BlockPos pos, PlayerEntity player, Hand hand, BlockRayTraceResult ray) {
         ItemStack heldItem = player.getHeldItem(hand);
 
-        if (AllBlocks.PISTON_EXTENSION_POLE.isIn(heldItem) && !player.isSneaking()) {
         IPlacementHelper placementHelper = PlacementHelpers.get(placementHelperId);
-            PlacementOffset offset = placementHelper.getOffset(world, state, pos, ray);
+        if (placementHelper.matchesItem(heldItem) && !player.isSneaking())
-
+            return placementHelper.getOffset(world, state, pos, ray).placeInWorld(world, (BlockItem) heldItem.getItem(), player, hand, ray);
-            if (!offset.isReplaceable(world))
-                return ActionResultType.PASS;
-
-            offset.placeInWorld(world, AllBlocks.PISTON_EXTENSION_POLE.getDefaultState(), player, heldItem);
-
-            /*BlockPos newPos = new BlockPos(offset.getPos());
-
-            if (world.isRemote)
-                return ActionResultType.SUCCESS;
-
-            world.setBlockState(newPos, offset.getTransform().apply(AllBlocks.PISTON_EXTENSION_POLE.getDefaultState()));
-            if (!player.isCreative())
-                heldItem.shrink(1);*/
-
-            return ActionResultType.SUCCESS;
-        }
 
         return ActionResultType.PASS;
     }

src/main/java/com/simibubi/create/content/contraptions/components/structureMovement/pulley/PulleyContraption.java

@@ -1,5 +1,6 @@
 package com.simibubi.create.content.contraptions.components.structureMovement.pulley;
 
+import com.simibubi.create.content.contraptions.components.structureMovement.AssemblyException;
 import com.simibubi.create.content.contraptions.components.structureMovement.ContraptionType;
 import com.simibubi.create.content.contraptions.components.structureMovement.TranslatingContraption;
 
@@ -23,7 +24,7 @@ public class PulleyContraption extends TranslatingContraption {
 	}
 
 	@Override
-	public boolean assemble(World world, BlockPos pos) {
+	public boolean assemble(World world, BlockPos pos) throws AssemblyException {
 		if (!searchMovedStructure(world, pos, null))
 			return false;
 		startMoving(world);

src/main/java/com/simibubi/create/content/contraptions/components/structureMovement/pulley/PulleyTileEntity.java

@@ -1,6 +1,7 @@
 package com.simibubi.create.content.contraptions.components.structureMovement.pulley;
 
 import com.simibubi.create.AllBlocks;
+import com.simibubi.create.content.contraptions.components.structureMovement.AssemblyException;
 import com.simibubi.create.content.contraptions.components.structureMovement.BlockMovementTraits;
 import com.simibubi.create.content.contraptions.components.structureMovement.ContraptionCollider;
 import com.simibubi.create.content.contraptions.components.structureMovement.ControlledContraptionEntity;
@@ -8,7 +9,6 @@ import com.simibubi.create.content.contraptions.components.structureMovement.pis
 import com.simibubi.create.foundation.config.AllConfigs;
 import com.simibubi.create.foundation.tileEntity.behaviour.CenteredSideValueBoxTransform;
 import com.simibubi.create.foundation.tileEntity.behaviour.ValueBoxTransform;
-
 import net.minecraft.block.BlockState;
 import net.minecraft.block.Blocks;
 import net.minecraft.block.IWaterLoggable;
@@ -42,7 +42,7 @@ public class PulleyTileEntity extends LinearActuatorTileEntity {
 	}
 
 	@Override
-	protected void assemble() {
+	protected void assemble() throws AssemblyException {
 		if (!(world.getBlockState(pos)
 			.getBlock() instanceof PulleyBlock))
 			return;
@@ -176,9 +176,10 @@ public class PulleyTileEntity extends LinearActuatorTileEntity {
 			return;
 
 		BlockPos posBelow = pos.down((int) (offset + getMovementSpeed()) + 1);
-		if (!BlockMovementTraits.movementNecessary(world, posBelow))
+		BlockState state = world.getBlockState(posBelow);
+		if (!BlockMovementTraits.movementNecessary(state, world, posBelow))
 			return;
-		if (BlockMovementTraits.isBrittle(world.getBlockState(posBelow)))
+		if (BlockMovementTraits.isBrittle(state))
 			return;
 
 		disassemble();

src/main/java/com/simibubi/create/content/contraptions/goggles/GoggleOverlayRenderer.java

@@ -4,6 +4,7 @@ import com.mojang.blaze3d.systems.RenderSystem;
 import com.simibubi.create.AllBlocks;
 import com.simibubi.create.AllItems;
 import com.simibubi.create.CreateClient;
+import com.simibubi.create.content.contraptions.components.structureMovement.IDisplayAssemblyExceptions;
 import com.simibubi.create.content.contraptions.components.structureMovement.piston.MechanicalPistonBlock;
 import com.simibubi.create.content.contraptions.components.structureMovement.piston.PistonExtensionPoleBlock;
 import com.simibubi.create.foundation.config.AllConfigs;
@@ -92,6 +93,14 @@ public class GoggleOverlayRenderer {
 				tooltip.remove(tooltip.size() - 1);
 		}
 
+		if (te instanceof IDisplayAssemblyExceptions) {
+			boolean exceptionAdded = ((IDisplayAssemblyExceptions) te).addExceptionToTooltip(tooltip);
+			if (exceptionAdded) {
+				hasHoveringInformation = true;
+				hoverAddedInformation = true;
+			}
+		}
+
 		// break early if goggle or hover returned false when present
 		if ((hasGoggleInformation && !goggleAddedInformation) && (hasHoveringInformation && !hoverAddedInformation))
 			return;

src/main/java/com/simibubi/create/content/contraptions/goggles/IHaveGoggleInformation.java

@@ -9,13 +9,13 @@ import java.util.List;
 public interface IHaveGoggleInformation {
 
 	DecimalFormat decimalFormat = new DecimalFormat("#.##");
-	public static String spacing = "    ";
+	String spacing = "    ";
 
 	/**
 	* this method will be called when looking at a TileEntity that implemented this interface
 	 *
-	 * @return {{@code true}} if the tooltip creation was successful and should be displayed,
+	 * @return {@code true} if the tooltip creation was successful and should be displayed,
-	 * or {{@code false}} if the overlay should not be displayed
+	 * or {@code false} if the overlay should not be displayed
 	* */
 	default boolean addToGoggleTooltip(List<String> tooltip, boolean isPlayerSneaking){
 		return false;

src/main/java/com/simibubi/create/content/contraptions/relays/advanced/GantryShaftBlock.java

@@ -1,9 +1,5 @@
 package com.simibubi.create.content.contraptions.relays.advanced;
 
-import java.util.ArrayList;
-import java.util.List;
-import java.util.function.Predicate;
-
 import com.simibubi.create.AllBlocks;
 import com.simibubi.create.AllShapes;
 import com.simibubi.create.AllTileEntities;
@@ -15,7 +11,6 @@ import com.simibubi.create.foundation.utility.placement.IPlacementHelper;
 import com.simibubi.create.foundation.utility.placement.PlacementHelpers;
 import com.simibubi.create.foundation.utility.placement.PlacementOffset;
 import com.simibubi.create.foundation.utility.placement.util.PoleHelper;
-
 import net.minecraft.block.Block;
 import net.minecraft.block.BlockRenderType;
 import net.minecraft.block.BlockState;
@@ -44,6 +39,10 @@ import net.minecraft.world.IWorld;
 import net.minecraft.world.IWorldReader;
 import net.minecraft.world.World;
 
+import java.util.ArrayList;
+import java.util.List;
+import java.util.function.Predicate;
+
 public class GantryShaftBlock extends DirectionalKineticBlock {
 
 	public static final IProperty<Part> PART = EnumProperty.create("part", Part.class);
@@ -66,22 +65,14 @@ public class GantryShaftBlock extends DirectionalKineticBlock {
 	}
 
 	@Override
-	public ActionResultType onUse(BlockState state, World world, BlockPos pos, PlayerEntity player, Hand hand,
+	public ActionResultType onUse(BlockState state, World world, BlockPos pos, PlayerEntity player, Hand hand, BlockRayTraceResult ray) {
-		BlockRayTraceResult ray) {
 		ItemStack heldItem = player.getHeldItem(hand);
 
 		IPlacementHelper placementHelper = PlacementHelpers.get(placementHelperId);
 		if (!placementHelper.matchesItem(heldItem))
 			return ActionResultType.PASS;
 
-		PlacementOffset offset = placementHelper.getOffset(world, state, pos, ray);
+		return placementHelper.getOffset(world, state, pos, ray).placeInWorld(world, ((BlockItem) heldItem.getItem()), player, hand, ray);
-
-		if (!offset.isReplaceable(world))
-			return ActionResultType.PASS;
-
-		offset.placeInWorld(world, ((BlockItem) heldItem.getItem()).getBlock()
-			.getDefaultState(), player, heldItem);
-		return ActionResultType.SUCCESS;
 	}
 
 	@Override

src/main/java/com/simibubi/create/content/contraptions/relays/advanced/SpeedControllerBlock.java

@@ -1,7 +1,5 @@
 package com.simibubi.create.content.contraptions.relays.advanced;
 
-import java.util.function.Predicate;
-
 import com.simibubi.create.AllBlocks;
 import com.simibubi.create.AllShapes;
 import com.simibubi.create.AllTileEntities;
@@ -13,11 +11,11 @@ import com.simibubi.create.foundation.utility.VecHelper;
 import com.simibubi.create.foundation.utility.placement.IPlacementHelper;
 import com.simibubi.create.foundation.utility.placement.PlacementHelpers;
 import com.simibubi.create.foundation.utility.placement.PlacementOffset;
-
 import mcp.MethodsReturnNonnullByDefault;
 import net.minecraft.block.Block;
 import net.minecraft.block.BlockState;
 import net.minecraft.entity.player.PlayerEntity;
+import net.minecraft.item.BlockItem;
 import net.minecraft.item.BlockItemUseContext;
 import net.minecraft.item.ItemStack;
 import net.minecraft.tileentity.TileEntity;
@@ -32,6 +30,8 @@ import net.minecraft.util.math.shapes.VoxelShape;
 import net.minecraft.world.IBlockReader;
 import net.minecraft.world.World;
 
+import java.util.function.Predicate;
+
 public class SpeedControllerBlock extends HorizontalAxisKineticBlock implements ITE<SpeedControllerTileEntity> {
 
 	private static final int placementHelperId = PlacementHelpers.register(new PlacementHelper());
@@ -67,19 +67,10 @@ public class SpeedControllerBlock extends HorizontalAxisKineticBlock implements
 	public ActionResultType onUse(BlockState state, World world, BlockPos pos, PlayerEntity player, Hand hand,
 		BlockRayTraceResult ray) {
 
-		IPlacementHelper helper = PlacementHelpers.get(placementHelperId);
 		ItemStack heldItem = player.getHeldItem(hand);
-		if (helper.matchesItem(heldItem)) {
+		IPlacementHelper helper = PlacementHelpers.get(placementHelperId);
-			PlacementOffset offset = helper.getOffset(world, state, pos, ray);
+		if (helper.matchesItem(heldItem))
-
+			return helper.getOffset(world, state, pos, ray).placeInWorld(world, (BlockItem) heldItem.getItem(), player, hand, ray);
-			if (!offset.isReplaceable(world))
-				return ActionResultType.PASS;
-
-			offset.placeInWorld(world, AllBlocks.LARGE_COGWHEEL.getDefaultState(), player, heldItem);
-
-			return ActionResultType.SUCCESS;
-
-		}
 
 		return ActionResultType.PASS;
 	}

src/main/java/com/simibubi/create/content/contraptions/relays/elementary/CogwheelBlockItem.java

@@ -1,10 +1,5 @@
 package com.simibubi.create.content.contraptions.relays.elementary;
 
-import static com.simibubi.create.content.contraptions.base.RotatedPillarKineticBlock.AXIS;
-
-import java.util.List;
-import java.util.function.Predicate;
-
 import com.simibubi.create.AllBlocks;
 import com.simibubi.create.AllShapes;
 import com.simibubi.create.content.contraptions.base.DirectionalKineticBlock;
@@ -16,13 +11,13 @@ import com.simibubi.create.foundation.utility.VecHelper;
 import com.simibubi.create.foundation.utility.placement.IPlacementHelper;
 import com.simibubi.create.foundation.utility.placement.PlacementHelpers;
 import com.simibubi.create.foundation.utility.placement.PlacementOffset;
-
 import mcp.MethodsReturnNonnullByDefault;
 import net.minecraft.block.BlockState;
 import net.minecraft.entity.player.PlayerEntity;
 import net.minecraft.item.BlockItem;
 import net.minecraft.item.BlockItemUseContext;
 import net.minecraft.item.ItemStack;
+import net.minecraft.item.ItemUseContext;
 import net.minecraft.util.ActionResultType;
 import net.minecraft.util.Direction;
 import net.minecraft.util.Direction.Axis;
@@ -31,6 +26,11 @@ import net.minecraft.util.math.BlockPos;
 import net.minecraft.util.math.BlockRayTraceResult;
 import net.minecraft.world.World;
 
+import java.util.List;
+import java.util.function.Predicate;
+
+import static com.simibubi.create.content.contraptions.base.RotatedPillarKineticBlock.AXIS;
+
 public class CogwheelBlockItem extends BlockItem {
 
 	boolean large;
@@ -47,49 +47,27 @@ public class CogwheelBlockItem extends BlockItem {
 	}
 
 	@Override
-	public ActionResultType tryPlace(BlockItemUseContext context) {
+	public ActionResultType onItemUseFirst(ItemStack stack, ItemUseContext context) {
 		World world = context.getWorld();
-		BlockPos pos = context.getPos()
+		BlockPos pos = context.getPos();
-			.offset(context.getFace()
-				.getOpposite());
 		BlockState state = world.getBlockState(pos);
 
 		IPlacementHelper helper = PlacementHelpers.get(placementHelperId);
 		PlayerEntity player = context.getPlayer();
-
+		BlockRayTraceResult ray = new BlockRayTraceResult(context.getHitVec(), context.getFace(), pos, true);
-		if (helper.matchesState(state)) {
+		if (helper.matchesState(state) && player != null && !player.isSneaking()) {
-			PlacementOffset offset = helper.getOffset(world, state, pos,
+			return helper.getOffset(world, state, pos, ray).placeInWorld(world, this, player, context.getHand(), ray);
-				new BlockRayTraceResult(context.getHitVec(), context.getFace(), pos, true));
-
-			if (!offset.isReplaceable(world))
-				return super.tryPlace(context);
-
-			offset.placeInWorld(world, this, player, context.getItem());
-			triggerShiftingGearsAdvancement(world, new BlockPos(offset.getPos()), offset.getTransform()
-				.apply(getBlock().getDefaultState()), player);
-
-			return ActionResultType.SUCCESS;
 		}
 
 		if (integratedCogHelperId != -1) {
 			helper = PlacementHelpers.get(integratedCogHelperId);
 
-			if (helper.matchesState(state)) {
+			if (helper.matchesState(state) && player != null && !player.isSneaking()) {
-				PlacementOffset offset = helper.getOffset(world, state, pos,
+				return helper.getOffset(world, state, pos, ray).placeInWorld(world, this, player, context.getHand(), ray);
-					new BlockRayTraceResult(context.getHitVec(), context.getFace(), pos, true));
-
-				if (!offset.isReplaceable(world))
-					return super.tryPlace(context);
-
-				offset.placeInWorld(world, this, player, context.getItem());
-				triggerShiftingGearsAdvancement(world, new BlockPos(offset.getPos()), offset.getTransform()
-					.apply(getBlock().getDefaultState()), player);
-
-				return ActionResultType.SUCCESS;
 			}
 		}
 
-		return super.tryPlace(context);
+		return super.onItemUseFirst(stack, context);
 	}
 
 	@Override

src/main/java/com/simibubi/create/content/contraptions/relays/elementary/ShaftBlock.java

@@ -7,7 +7,6 @@ import com.simibubi.create.content.contraptions.relays.encased.EncasedShaftBlock
 import com.simibubi.create.foundation.advancement.AllTriggers;
 import com.simibubi.create.foundation.utility.placement.IPlacementHelper;
 import com.simibubi.create.foundation.utility.placement.PlacementHelpers;
-import com.simibubi.create.foundation.utility.placement.PlacementOffset;
 import com.simibubi.create.foundation.utility.placement.util.PoleHelper;
 import mcp.MethodsReturnNonnullByDefault;
 import net.minecraft.block.BlockState;
@@ -77,26 +76,8 @@ public class ShaftBlock extends AbstractShaftBlock {
 		}
 
 		IPlacementHelper helper = PlacementHelpers.get(placementHelperId);
-		if (helper.getItemPredicate().test(heldItem)) {
+		if (helper.matchesItem(heldItem))
-			PlacementOffset offset = helper.getOffset(world, state, pos, ray);
+			return helper.getOffset(world, state, pos, ray).placeInWorld(world, (BlockItem) heldItem.getItem(), player, hand, ray);
-
-			if (!offset.isReplaceable(world))
-				return ActionResultType.PASS;
-
-			offset.placeInWorld(world, (BlockItem) heldItem.getItem(), player, heldItem);
-
-			/*BlockPos newPos = new BlockPos(offset.getPos());
-
-			if (world.isRemote)
-				return ActionResultType.SUCCESS;
-
-			Block block = ((BlockItem) heldItem.getItem()).getBlock();
-			world.setBlockState(newPos, offset.getTransform().apply(block.getDefaultState()));
-			if (!player.isCreative())
-				heldItem.shrink(1);*/
-
-			return ActionResultType.SUCCESS;
-		}
 
 		return ActionResultType.PASS;
 	}

src/main/java/com/simibubi/create/foundation/command/AllCommands.java

@@ -1,25 +1,42 @@
 package com.simibubi.create.foundation.command;
 
 import com.mojang.brigadier.CommandDispatcher;
-
+import com.mojang.brigadier.tree.CommandNode;
+import com.mojang.brigadier.tree.LiteralCommandNode;
 import net.minecraft.command.CommandSource;
 import net.minecraft.command.Commands;
+import net.minecraft.entity.player.PlayerEntity;
+
+import java.util.Collections;
+import java.util.function.Predicate;
 
 public class AllCommands {
 
+	public static Predicate<CommandSource> sourceIsPlayer = (cs) -> cs.getEntity() instanceof PlayerEntity;
+
 	public static void register(CommandDispatcher<CommandSource> dispatcher) {
-		dispatcher.register(Commands.literal("create")
+
+		LiteralCommandNode<CommandSource> createRoot = dispatcher.register(Commands.literal("create")
 						//general purpose
 						.then(ToggleDebugCommand.register())
 						.then(OverlayConfigCommand.register())
 						.then(FixLightingCommand.register())
 						.then(ReplaceInCommandBlocksCommand.register())
+						.then(HighlightCommand.register())
 
 						//dev-util
 						//Comment out for release
 						.then(ClearBufferCacheCommand.register())
 						.then(ChunkUtilCommand.register())
-//		      .then(KillTPSCommand.register())
+						//.then(KillTPSCommand.register())
+		);
+
+		CommandNode<CommandSource> c = dispatcher.findNode(Collections.singleton("c"));
+		if (c != null)
+			return;
+
+		dispatcher.register(Commands.literal("c")
+				.redirect(createRoot)
 		);
 	}
 }

src/main/java/com/simibubi/create/foundation/command/HighlightCommand.java

@@ -0,0 +1,103 @@
+package com.simibubi.create.foundation.command;
+
+import com.mojang.brigadier.Command;
+import com.mojang.brigadier.builder.ArgumentBuilder;
+import com.simibubi.create.content.contraptions.components.structureMovement.AssemblyException;
+import com.simibubi.create.content.contraptions.components.structureMovement.IDisplayAssemblyExceptions;
+import com.simibubi.create.foundation.networking.AllPackets;
+import net.minecraft.command.CommandSource;
+import net.minecraft.command.Commands;
+import net.minecraft.command.arguments.BlockPosArgument;
+import net.minecraft.command.arguments.EntityArgument;
+import net.minecraft.entity.player.PlayerEntity;
+import net.minecraft.entity.player.ServerPlayerEntity;
+import net.minecraft.tileentity.TileEntity;
+import net.minecraft.util.math.*;
+import net.minecraft.util.text.StringTextComponent;
+import net.minecraft.world.World;
+import net.minecraftforge.fml.network.PacketDistributor;
+
+import java.util.Collection;
+
+public class HighlightCommand {
+
+	public static ArgumentBuilder<CommandSource, ?> register() {
+		return Commands.literal("highlight")
+				.requires(cs -> cs.hasPermissionLevel(0))
+				.requires(AllCommands.sourceIsPlayer)
+				.then(Commands.argument("pos", BlockPosArgument.blockPos())
+						.requires(AllCommands.sourceIsPlayer)
+						.executes(ctx -> {
+							BlockPos pos = BlockPosArgument.getLoadedBlockPos(ctx, "pos");
+
+							AllPackets.channel.send(
+									PacketDistributor.PLAYER.with(() -> (ServerPlayerEntity) ctx.getSource().getEntity()),
+									new HighlightPacket(pos)
+							);
+
+							return Command.SINGLE_SUCCESS;
+						})
+						.then(Commands.argument("players", EntityArgument.players())
+								.executes(ctx -> {
+									Collection<ServerPlayerEntity> players = EntityArgument.getPlayers(ctx, "players");
+									BlockPos pos = BlockPosArgument.getBlockPos(ctx, "pos");
+
+									for (ServerPlayerEntity p : players) {
+										AllPackets.channel.send(
+												PacketDistributor.PLAYER.with(() -> p),
+												new HighlightPacket(pos)
+										);
+									}
+
+									return players.size();
+								})
+						)
+				)
+				.executes(ctx -> {
+					ServerPlayerEntity player = ctx.getSource().asPlayer();
+					return highlightAssemblyExceptionFor(player, ctx.getSource());
+				});
+
+	}
+
+	private static void sendMissMessage(CommandSource source) {
+		source.sendFeedback(new StringTextComponent("Try looking at a Block that has failed to assemble a Contraption and try again."), true);
+	}
+
+	private static int highlightAssemblyExceptionFor(ServerPlayerEntity player, CommandSource source) {
+		double distance = player.getAttribute(PlayerEntity.REACH_DISTANCE).getValue();
+		Vec3d start = player.getEyePosition(1);
+		Vec3d look = player.getLook(1);
+		Vec3d end = start.add(look.x * distance, look.y * distance, look.z * distance);
+		World world = player.world;
+
+		BlockRayTraceResult ray = world.rayTraceBlocks(new RayTraceContext(start, end, RayTraceContext.BlockMode.OUTLINE, RayTraceContext.FluidMode.NONE, player));
+		if (ray.getType() == RayTraceResult.Type.MISS) {
+			sendMissMessage(source);
+			return 0;
+		}
+
+		BlockPos pos = ray.getPos();
+		TileEntity te = world.getTileEntity(pos);
+		if (!(te instanceof IDisplayAssemblyExceptions)) {
+			sendMissMessage(source);
+			return 0;
+		}
+
+		IDisplayAssemblyExceptions display = (IDisplayAssemblyExceptions) te;
+		AssemblyException exception = display.getLastAssemblyException();
+		if (exception == null) {
+			sendMissMessage(source);
+			return 0;
+		}
+
+		if (!exception.hasPosition()) {
+			source.sendFeedback(new StringTextComponent("Can't highlight a specific position for this issue"), true);
+			return Command.SINGLE_SUCCESS;
+		}
+
+		BlockPos p = exception.getPosition();
+		String command = "/create highlight " + p.getX() + " " + p.getY() + " " + p.getZ();
+		return player.server.getCommandManager().handleCommand(source, command);
+	}
+}

src/main/java/com/simibubi/create/foundation/command/HighlightPacket.java

@@ -0,0 +1,55 @@
+package com.simibubi.create.foundation.command;
+
+import com.simibubi.create.AllSpecialTextures;
+import com.simibubi.create.CreateClient;
+import com.simibubi.create.foundation.networking.SimplePacketBase;
+import net.minecraft.client.Minecraft;
+import net.minecraft.network.PacketBuffer;
+import net.minecraft.util.math.BlockPos;
+import net.minecraft.util.math.shapes.VoxelShapes;
+import net.minecraftforge.api.distmarker.Dist;
+import net.minecraftforge.api.distmarker.OnlyIn;
+import net.minecraftforge.fml.DistExecutor;
+import net.minecraftforge.fml.network.NetworkEvent;
+
+import java.util.function.Supplier;
+
+public class HighlightPacket extends SimplePacketBase {
+
+	private final BlockPos pos;
+
+	public HighlightPacket(BlockPos pos) {
+		this.pos = pos;
+	}
+
+	public HighlightPacket(PacketBuffer buffer) {
+		this.pos = BlockPos.fromLong(buffer.readLong());
+	}
+
+	@Override
+	public void write(PacketBuffer buffer) {
+		buffer.writeLong(pos.toLong());
+	}
+
+	@Override
+	public void handle(Supplier<NetworkEvent.Context> ctx) {
+		ctx.get().enqueueWork(() -> DistExecutor.runWhenOn(Dist.CLIENT, () -> () -> {
+			performHighlight(pos);
+		}));
+
+		ctx.get().setPacketHandled(true);
+	}
+
+	@OnlyIn(Dist.CLIENT)
+	public static void performHighlight(BlockPos pos) {
+		if (Minecraft.getInstance().world == null || !Minecraft.getInstance().world.isBlockPresent(pos))
+			return;
+
+		CreateClient.outliner.showAABB("highlightCommand", VoxelShapes.fullCube().getBoundingBox().offset(pos), 200)
+				.lineWidth(1 / 32f)
+				.colored(0xEeEeEe)
+				//.colored(0x243B50)
+				.withFaceTexture(AllSpecialTextures.SELECTION);
+
+	}
+}

src/main/java/com/simibubi/create/foundation/networking/AllPackets.java

@@ -1,19 +1,11 @@
 package com.simibubi.create.foundation.networking;
 
-import java.util.function.BiConsumer;
-import java.util.function.Function;
-import java.util.function.Supplier;
-
 import com.simibubi.create.Create;
 import com.simibubi.create.content.contraptions.components.structureMovement.ContraptionDisassemblyPacket;
 import com.simibubi.create.content.contraptions.components.structureMovement.ContraptionStallPacket;
 import com.simibubi.create.content.contraptions.components.structureMovement.gantry.GantryContraptionUpdatePacket;
 import com.simibubi.create.content.contraptions.components.structureMovement.glue.GlueEffectPacket;
-import com.simibubi.create.content.contraptions.components.structureMovement.sync.ClientMotionPacket;
+import com.simibubi.create.content.contraptions.components.structureMovement.sync.*;
-import com.simibubi.create.content.contraptions.components.structureMovement.sync.ContraptionFluidPacket;
-import com.simibubi.create.content.contraptions.components.structureMovement.sync.ContraptionInteractionPacket;
-import com.simibubi.create.content.contraptions.components.structureMovement.sync.ContraptionSeatMappingPacket;
-import com.simibubi.create.content.contraptions.components.structureMovement.sync.LimbSwingUpdatePacket;
 import com.simibubi.create.content.contraptions.components.structureMovement.train.CouplingCreationPacket;
 import com.simibubi.create.content.contraptions.components.structureMovement.train.capability.MinecartControllerUpdatePacket;
 import com.simibubi.create.content.contraptions.fluids.actors.FluidSplashPacket;
@@ -25,16 +17,12 @@ import com.simibubi.create.content.logistics.block.mechanicalArm.ArmPlacementPac
 import com.simibubi.create.content.logistics.item.filter.FilterScreenPacket;
 import com.simibubi.create.content.logistics.packet.ConfigureFlexcratePacket;
 import com.simibubi.create.content.logistics.packet.ConfigureStockswitchPacket;
-import com.simibubi.create.content.schematics.packet.ConfigureSchematicannonPacket;
+import com.simibubi.create.content.schematics.packet.*;
-import com.simibubi.create.content.schematics.packet.InstantSchematicPacket;
-import com.simibubi.create.content.schematics.packet.SchematicPlacePacket;
-import com.simibubi.create.content.schematics.packet.SchematicSyncPacket;
-import com.simibubi.create.content.schematics.packet.SchematicUploadPacket;
 import com.simibubi.create.foundation.command.ConfigureConfigPacket;
+import com.simibubi.create.foundation.command.HighlightPacket;
 import com.simibubi.create.foundation.tileEntity.behaviour.filtering.FilteringCountUpdatePacket;
 import com.simibubi.create.foundation.tileEntity.behaviour.scrollvalue.ScrollValueUpdatePacket;
 import com.simibubi.create.foundation.utility.ServerSpeedProvider;
-
 import net.minecraft.network.PacketBuffer;
 import net.minecraft.util.ResourceLocation;
 import net.minecraft.util.math.BlockPos;
@@ -46,8 +34,12 @@ import net.minecraftforge.fml.network.PacketDistributor;
 import net.minecraftforge.fml.network.PacketDistributor.TargetPoint;
 import net.minecraftforge.fml.network.simple.SimpleChannel;
 
-import static net.minecraftforge.fml.network.NetworkDirection.PLAY_TO_SERVER;
+import java.util.function.BiConsumer;
+import java.util.function.Function;
+import java.util.function.Supplier;
+
 import static net.minecraftforge.fml.network.NetworkDirection.PLAY_TO_CLIENT;
+import static net.minecraftforge.fml.network.NetworkDirection.PLAY_TO_SERVER;
 
 public enum AllPackets {
 
@@ -85,6 +77,7 @@ public enum AllPackets {
 	FLUID_SPLASH(FluidSplashPacket.class, FluidSplashPacket::new, PLAY_TO_CLIENT),
 	CONTRAPTION_FLUID(ContraptionFluidPacket.class, ContraptionFluidPacket::new, PLAY_TO_CLIENT),
 	GANTRY_UPDATE(GantryContraptionUpdatePacket.class, GantryContraptionUpdatePacket::new, PLAY_TO_CLIENT),
+	BLOCK_HIGHLIGHT(HighlightPacket.class, HighlightPacket::new, PLAY_TO_CLIENT)
 
 	;
 

src/main/java/com/simibubi/create/foundation/utility/outliner/Outliner.java

@@ -1,24 +1,18 @@
 package com.simibubi.create.foundation.utility.outliner;
 
-import java.util.Collections;
-import java.util.HashMap;
-import java.util.HashSet;
-import java.util.Map;
-import java.util.Optional;
-import java.util.Set;
-
 import com.mojang.blaze3d.matrix.MatrixStack;
 import com.simibubi.create.foundation.renderState.SuperRenderTypeBuffer;
 import com.simibubi.create.foundation.tileEntity.behaviour.ValueBox;
 import com.simibubi.create.foundation.utility.outliner.LineOutline.EndChasingLineOutline;
 import com.simibubi.create.foundation.utility.outliner.Outline.OutlineParams;
-
 import net.minecraft.client.Minecraft;
 import net.minecraft.util.math.AxisAlignedBB;
 import net.minecraft.util.math.BlockPos;
 import net.minecraft.util.math.MathHelper;
 import net.minecraft.util.math.Vec3d;
 
+import java.util.*;
+
 public class Outliner {
 
 	final Map<Object, OutlineEntry> outlines;
@@ -57,6 +51,13 @@ public class Outliner {
 		return entry.outline.getParams();
 	}
 
+	public OutlineParams showAABB(Object slot, AxisAlignedBB bb, int ttl) {
+		createAABBOutlineIfMissing(slot, bb);
+		ChasingAABBOutline outline = getAndRefreshAABB(slot, ttl);
+		outline.prevBB = outline.targetBB = bb;
+		return outline.getParams();
+	}
+
 	public OutlineParams showAABB(Object slot, AxisAlignedBB bb) {
 		createAABBOutlineIfMissing(slot, bb);
 		ChasingAABBOutline outline = getAndRefreshAABB(slot);
@@ -112,6 +113,12 @@ public class Outliner {
 		return (ChasingAABBOutline) entry.getOutline();
 	}
 
+	private ChasingAABBOutline getAndRefreshAABB(Object slot, int ttl) {
+		OutlineEntry entry = outlines.get(slot);
+		entry.ticksTillRemoval = ttl;
+		return (ChasingAABBOutline) entry.getOutline();
+	}
+
 	// Maintenance
 
 	public Outliner() {

src/main/java/com/simibubi/create/foundation/utility/placement/IPlacementHelper.java

@@ -6,6 +6,7 @@ import com.simibubi.create.foundation.utility.Pair;
 import com.simibubi.create.foundation.utility.VecHelper;
 import mcp.MethodsReturnNonnullByDefault;
 import net.minecraft.block.BlockState;
+import net.minecraft.block.Blocks;
 import net.minecraft.item.ItemStack;
 import net.minecraft.util.Direction;
 import net.minecraft.util.math.BlockPos;
@@ -22,6 +23,11 @@ import java.util.stream.Collectors;
 @MethodsReturnNonnullByDefault
 public interface IPlacementHelper {
 
+	/**
+	 * used as an identifier in SuperGlueHandler to skip blocks placed by helpers
+	 */
+	BlockState ID = new BlockState(Blocks.AIR, null);
+
 	/**
 	 * @return a predicate that gets tested with the items held in the players hands,
 	 * should return true if this placement helper is active with the given item
@@ -61,24 +67,6 @@ public interface IPlacementHelper {
 		CreateClient.outliner.showLine("placementArrowB" + center + target, start.add(offset), endB.add(offset)).lineWidth(1/16f);
 	}
 
-	/*@OnlyIn(Dist.CLIENT)
-	static void renderArrow(Vec3d center, Direction towards, BlockRayTraceResult ray) {
-		Direction hitFace = ray.getFace();
-
-		if (hitFace.getAxis() == towards.getAxis())
-			return;
-
-		//get the two perpendicular directions to form the arrow
-		Direction[] directions = Arrays.stream(Direction.Axis.values()).filter(axis -> axis != hitFace.getAxis() && axis != towards.getAxis()).map(Iterate::directionsInAxis).findFirst().orElse(new Direction[]{});
-		Vec3d startOffset = new Vec3d(towards.getDirectionVec());
-		Vec3d start = center.add(startOffset);
-		for (Direction dir : directions) {
-			Vec3d arrowOffset = new Vec3d(dir.getDirectionVec()).scale(.25);
-			Vec3d target = center.add(startOffset.scale(0.75)).add(arrowOffset);
-			CreateClient.outliner.showLine("placementArrow" + towards + dir, start, target).lineWidth(1/16f);
-		}
-	}*/
-
 	static List<Direction> orderedByDistanceOnlyAxis(BlockPos pos, Vec3d hit, Direction.Axis axis) {
 		return orderedByDistance(pos, hit, dir -> dir.getAxis() == axis);
 	}

src/main/java/com/simibubi/create/foundation/utility/placement/PlacementOffset.java

@@ -1,15 +1,26 @@
 package com.simibubi.create.foundation.utility.placement;
 
+import net.minecraft.advancements.CriteriaTriggers;
 import net.minecraft.block.BlockState;
+import net.minecraft.block.SoundType;
 import net.minecraft.entity.player.PlayerEntity;
+import net.minecraft.entity.player.ServerPlayerEntity;
 import net.minecraft.fluid.Fluids;
 import net.minecraft.fluid.IFluidState;
 import net.minecraft.item.BlockItem;
-import net.minecraft.item.ItemStack;
+import net.minecraft.item.ItemUseContext;
 import net.minecraft.state.properties.BlockStateProperties;
+import net.minecraft.stats.Stats;
+import net.minecraft.util.ActionResultType;
+import net.minecraft.util.Hand;
+import net.minecraft.util.SoundCategory;
 import net.minecraft.util.math.BlockPos;
+import net.minecraft.util.math.BlockRayTraceResult;
 import net.minecraft.util.math.Vec3i;
 import net.minecraft.world.World;
+import net.minecraftforge.common.MinecraftForge;
+import net.minecraftforge.common.util.BlockSnapshot;
+import net.minecraftforge.event.world.BlockEvent;
 
 import java.util.function.Function;
 
@@ -56,24 +67,48 @@ public class PlacementOffset {
 		return world.getBlockState(new BlockPos(pos)).getMaterial().isReplaceable();
 	}
 	
-	public void placeInWorld(World world, BlockItem blockItem, PlayerEntity player, ItemStack item) {
+	public ActionResultType placeInWorld(World world, BlockItem blockItem, PlayerEntity player, Hand hand, BlockRayTraceResult ray) {
-		placeInWorld(world, blockItem.getBlock().getDefaultState(), player, item);
-	}
 
-	public void placeInWorld(World world, BlockState defaultState, PlayerEntity player, ItemStack item) {
+		ItemUseContext context = new ItemUseContext(player, hand, ray);
-		if (world.isRemote)
-			return;
 
 		BlockPos newPos = new BlockPos(pos);
-		BlockState state = stateTransform.apply(defaultState);
+
+		if (!world.isBlockModifiable(player, newPos))
+			return ActionResultType.PASS;
+
+		if (!isReplaceable(world))
+			return ActionResultType.PASS;
+
+		BlockState state = stateTransform.apply(blockItem.getBlock().getDefaultState());
 		if (state.has(BlockStateProperties.WATERLOGGED)) {
 			IFluidState fluidState = world.getFluidState(newPos);
 			state = state.with(BlockStateProperties.WATERLOGGED, fluidState.getFluid() == Fluids.WATER);
 		}
 
+		BlockSnapshot snapshot = BlockSnapshot.getBlockSnapshot(world, newPos);
 		world.setBlockState(newPos, state);
 
+		BlockEvent.EntityPlaceEvent event = new BlockEvent.EntityPlaceEvent(snapshot, IPlacementHelper.ID, player);
+		if (MinecraftForge.EVENT_BUS.post(event)) {
+			snapshot.restore(true, false);
+			return ActionResultType.FAIL;
+		}
+
+		BlockState newState = world.getBlockState(newPos);
+		SoundType soundtype = newState.getSoundType(world, newPos, player);
+		world.playSound(player, newPos, soundtype.getPlaceSound(), SoundCategory.BLOCKS, (soundtype.getVolume() + 1.0F) / 2.0F, soundtype.getPitch() * 0.8F);
+
+		player.addStat(Stats.ITEM_USED.get(blockItem));
+
+		if (world.isRemote)
+			return ActionResultType.SUCCESS;
+
+		if (player instanceof ServerPlayerEntity)
+			CriteriaTriggers.PLACED_BLOCK.trigger((ServerPlayerEntity) player, newPos, context.getItem());
+
 		if (!player.isCreative())
-			item.shrink(1);
+			context.getItem().shrink(1);
+
+		return ActionResultType.SUCCESS;
 	}
 }

src/main/resources/assets/create/lang/default/messages.json

@@ -172,6 +172,13 @@
 	"create.gui.goggles.at_current_speed": "at current speed",
 	"create.gui.goggles.pole_length": "Pole Length:",
 
+	"create.gui.assembly.exception": "This Contraption was unable to assemble:",
+	"create.gui.assembly.exception.unmovableBlock": "Unmovable Block (%4$s) at [%1$s %2$s %3$s]",
+	"create.gui.assembly.exception.chunkNotLoaded": "The Block at [%1$s %2$s %3$s] was not in a loaded chunk",
+	"create.gui.assembly.exception.structureTooLarge": "There are too many Blocks included in the contraption.\nThe configured maximum is: %1$s",
+	"create.gui.assembly.exception.tooManyPistonPoles": "There are too many extension Poles attached to this Piston.\nThe configured maximum is: %1$s",
+	"create.gui.assembly.exception.noPistonPoles": "The Piston is missing some extension Poles",
+
 	"create.gui.gauge.info_header": "Gauge Information:",
 	"create.gui.speedometer.title": "Rotation Speed",
 	"create.gui.stressometer.title": "Network Stress",