diff --git a/core/src/mindustry/content/Blocks.java b/core/src/mindustry/content/Blocks.java
index 3a9084657c..9170acb910 100644
--- a/core/src/mindustry/content/Blocks.java
+++ b/core/src/mindustry/content/Blocks.java
@@ -3312,6 +3312,7 @@ public class Blocks{
         //endregion
         //region units - erekir
 
+        //TODO 5x5?
         //TODO completely unfinished
         tankAssembler = new UnitAssembler("tank-assembler"){{
             requirements(Category.units, with(Items.graphite, 10));
diff --git a/core/src/mindustry/entities/EntityCollisions.java b/core/src/mindustry/entities/EntityCollisions.java
index f29a2c67f3..233f3760e5 100644
--- a/core/src/mindustry/entities/EntityCollisions.java
+++ b/core/src/mindustry/entities/EntityCollisions.java
@@ -4,6 +4,7 @@ import arc.func.*;
 import arc.math.*;
 import arc.math.geom.*;
 import arc.struct.*;
+import arc.util.*;
 import mindustry.content.*;
 import mindustry.gen.*;
 import mindustry.world.*;
@@ -94,9 +95,11 @@ public class EntityCollisions{
         entity.trns(r1.x - r2.x, r1.y - r2.y);
     }
 
-    public boolean overlapsTile(Rect rect){
+    public boolean overlapsTile(Rect rect, @Nullable SolidPred solidChecker){
+        if(solidChecker == null) return false;
+
         rect.getCenter(vector);
-        int r = 1;
+        int r = Math.max(Math.round(r1.width / tilesize), 1);
 
         //assumes tiles are centered
         int tilex = Math.round(vector.x / tilesize);
@@ -105,10 +108,9 @@ public class EntityCollisions{
         for(int dx = -r; dx <= r; dx++){
             for(int dy = -r; dy <= r; dy++){
                 int wx = dx + tilex, wy = dy + tiley;
-                if(solid(wx, wy)){
-                    r2.setSize(tilesize).setCenter(wx * tilesize, wy * tilesize);
+                if(solidChecker.solid(wx, wy)){
 
-                    if(r2.overlaps(rect)){
+                    if(r2.setCentered(wx * tilesize, wy * tilesize, tilesize).overlaps(rect)){
                         return true;
                     }
                 }
diff --git a/core/src/mindustry/entities/Units.java b/core/src/mindustry/entities/Units.java
index 2c5797067d..b07022ef70 100644
--- a/core/src/mindustry/entities/Units.java
+++ b/core/src/mindustry/entities/Units.java
@@ -135,6 +135,10 @@ public class Units{
         return anyEntities(tile, true);
     }
 
+    public static boolean anyEntities(float x, float y, float size){
+        return anyEntities(x - size/2f, y - size/2f, size, size, true);
+    }
+
     public static boolean anyEntities(float x, float y, float width, float height){
         return anyEntities(x, y, width, height, true);
     }
diff --git a/core/src/mindustry/entities/comp/BuildingComp.java b/core/src/mindustry/entities/comp/BuildingComp.java
index 4c6f90b4b0..81d901e53b 100644
--- a/core/src/mindustry/entities/comp/BuildingComp.java
+++ b/core/src/mindustry/entities/comp/BuildingComp.java
@@ -783,6 +783,10 @@ abstract class BuildingComp implements Posc, Teamc, Healthc, Buildingc, Timerc,
         return null;
     }
 
+    public @Nullable BlockSeq getBlockPayloads(){
+        return null;
+    }
+
     /**
      * Tries to put this item into a nearby container, if there are no available
      * containers, it gets added to the block's inventory.
diff --git a/core/src/mindustry/graphics/Drawf.java b/core/src/mindustry/graphics/Drawf.java
index 2d926685fc..3d5f2f2b8e 100644
--- a/core/src/mindustry/graphics/Drawf.java
+++ b/core/src/mindustry/graphics/Drawf.java
@@ -84,9 +84,9 @@ public class Drawf{
 
     public static void dashRect(Color color, Rect rect){
         dashLine(color, rect.x, rect.y, rect.x + rect.width, rect.y);
-        dashLine(color, rect.x, rect.y, rect.x, rect.y + rect.height);
         dashLine(color, rect.x + rect.width, rect.y, rect.x + rect.width, rect.y + rect.height);
-        dashLine(color, rect.x, rect.y + rect.height, rect.x + rect.width, rect.y + rect.height);
+        dashLine(color, rect.x + rect.width, rect.y + rect.height, rect.x, rect.y + rect.height);
+        dashLine(color, rect.x, rect.y + rect.height, rect.x, rect.y);
     }
 
     public static void target(float x, float y, float rad, Color color){
diff --git a/core/src/mindustry/input/MobileInput.java b/core/src/mindustry/input/MobileInput.java
index 26b686490a..6df756df91 100644
--- a/core/src/mindustry/input/MobileInput.java
+++ b/core/src/mindustry/input/MobileInput.java
@@ -917,9 +917,9 @@ public class MobileInput extends InputHandler implements GestureListener{
         }
 
         unit.hitbox(rect);
-        rect.grow(6f);
+        rect.grow(4f);
 
-        player.boosting = collisions.overlapsTile(rect) || !unit.within(targetPos, 85f);
+        player.boosting = collisions.overlapsTile(rect, unit.solidity()) || !unit.within(targetPos, 85f);
 
         unit.movePref(movement);
 
diff --git a/core/src/mindustry/world/blocks/units/UnitAssembler.java b/core/src/mindustry/world/blocks/units/UnitAssembler.java
index 4cc31aac30..bdf86ecb8e 100644
--- a/core/src/mindustry/world/blocks/units/UnitAssembler.java
+++ b/core/src/mindustry/world/blocks/units/UnitAssembler.java
@@ -1,6 +1,7 @@
 package mindustry.world.blocks.units;
 
 import arc.*;
+import arc.graphics.*;
 import arc.graphics.g2d.*;
 import arc.math.*;
 import arc.math.geom.*;
@@ -40,6 +41,7 @@ public class UnitAssembler extends PayloadBlock{
         update = solid = true;
         rotate = true;
         rotateDraw = false;
+        acceptsPayload = true;
     }
 
     @Override
@@ -87,7 +89,7 @@ public class UnitAssembler extends PayloadBlock{
 
     @Override
     public void init(){
-        consumes.add(new ConsumePayloads(requirements, (UnitAssemblerBuild build) -> build.blocks));
+        consumes.add(new ConsumePayloads(requirements));
 
         super.init();
     }
@@ -96,6 +98,8 @@ public class UnitAssembler extends PayloadBlock{
         public Seq<Unit> units = new Seq<>();
         public BlockSeq blocks = new BlockSeq();
 
+        public boolean wasOccupied = false;
+
         //TODO progress
         //TODO how should payloads be stored exactly? counts of blocks? intmap? references?
 
@@ -130,8 +134,10 @@ public class UnitAssembler extends PayloadBlock{
 
             Vec2 spawn = getUnitSpawn();
 
+            wasOccupied = checkSolid(spawn);
+
             //check if all requirements are met
-            if(consValid() & Units.canCreate(team, output)){
+            if(!wasOccupied && consValid() & Units.canCreate(team, output)){
 
                 //TODO ???? should this even be part of a trigger
                 consume();
@@ -172,9 +178,23 @@ public class UnitAssembler extends PayloadBlock{
             Draw.mixcol(Pal.accent, 1f);
             Draw.alpha(0.4f + Mathf.absin(10f, 0.2f));
             Draw.rect(output.fullIcon, spawn.x, spawn.y);
+
+            //TODO dash rect for output, fades in/out
+            Draw.color(!wasOccupied ? Color.green : Color.red);
+            Lines.square(spawn.x, spawn.y, output.hitSize/2f);
+
             Draw.reset();
         }
 
+        public boolean checkSolid(Vec2 v){
+            return !output.flying && (collisions.overlapsTile(Tmp.r1.setCentered(v.x, v.y, output.hitSize), EntityCollisions::solid) || Units.anyEntities(v.x, v.y, output.hitSize));
+        }
+
+        @Override
+        public BlockSeq getBlockPayloads(){
+            return blocks;
+        }
+
         @Override
         public void handlePayload(Building source, Payload payload){
             //super.handlePayload(source, payload);
@@ -184,6 +204,7 @@ public class UnitAssembler extends PayloadBlock{
             //payloads.add((BuildPayload)payload);
         }
 
+        //TODO doesn't accept from payload source
         @Override
         public boolean acceptPayload(Building source, Payload payload){
             return payload instanceof BuildPayload bp && requirements.contains(b -> b.block == bp.block() && blocks.get(bp.block()) < b.amount);
diff --git a/core/src/mindustry/world/consumers/ConsumePayloads.java b/core/src/mindustry/world/consumers/ConsumePayloads.java
index b45cfae90a..67606cbea8 100644
--- a/core/src/mindustry/world/consumers/ConsumePayloads.java
+++ b/core/src/mindustry/world/consumers/ConsumePayloads.java
@@ -9,24 +9,20 @@ import mindustry.ui.*;
 import mindustry.world.meta.*;
 
 public class ConsumePayloads extends Consume{
-    //TODO bad, should be part of Building + dynamic
-    protected Func<Building, BlockSeq> inventory;
-
     public Seq<BlockStack> payloads;
 
-    public <T extends Building> ConsumePayloads(Seq<BlockStack> payloads, Func<T, BlockSeq> inventory){
+    public <T extends Building> ConsumePayloads(Seq<BlockStack> payloads){
         this.payloads = payloads;
-        this.inventory = (Func<Building, BlockSeq>)inventory;
     }
 
     @Override
     public boolean valid(Building build){
-        return inventory.get(build).contains(payloads);
+        return build.getBlockPayloads().contains(payloads);
     }
 
     @Override
     public void trigger(Building build){
-        inventory.get(build).remove(payloads);
+        build.getBlockPayloads().remove(payloads);
     }
 
     @Override
@@ -43,7 +39,7 @@ public class ConsumePayloads extends Consume{
 
     @Override
     public void build(Building build, Table table){
-        var inv = inventory.get(build);
+        var inv = build.getBlockPayloads();
 
         table.table(c -> {
             int i = 0;
diff --git a/tools/src/mindustry/tools/Generators.java b/tools/src/mindustry/tools/Generators.java
index 13acaba85f..3941217b88 100644
--- a/tools/src/mindustry/tools/Generators.java
+++ b/tools/src/mindustry/tools/Generators.java
@@ -559,6 +559,12 @@ public class Generators{
                     replace(type.name, image);
                 }
 
+                //draw treads
+                if(sample instanceof Tankc){
+                    image.draw(get(type.treadRegion), true);
+                    image.draw(get(type.region), true);
+                }
+
                 //draw mech parts
                 if(sample instanceof Mechc){
                     drawCenter(image, get(type.baseRegion));