diff --git a/scene/lobby.pr b/scene/lobby.pr
index 14c16c6..4691427 100644
--- a/scene/lobby.pr
+++ b/scene/lobby.pr
@@ -106,7 +106,7 @@
 ;     >>>>>
 
 <sprite "tt2" []
- <move <v 0.0 1.6 3.0>
+ <move <v 0.0 1.6 5.2>
   <color 0.5 0.0 1.0
    <turtle [
      1 to slen
@@ -128,29 +128,46 @@
    ]>>>>
 
 <sprite "tt" []
- <move <v 1.0 0.01 0.75>
+ <move <v 1.0 1.01 0.75>
   <rotate <v -0.125 0.0 0.0>
    <texture ["textures/oak-herringbone-5e80fb40b00c9-1200.jpg"
              <v 2.0 1.0>
              <v 0.0 0.0>
              1.0]
-    <turtle [
-      1.0 to wallHeight
-      0.1 to wallDepth
+    <csg
+     <subtract [
+       <mesh
+        <turtle [
+          1.0 to wallHeight
+          0.1 to wallDepth
 
-      90 U
-      PenDown
-      [wallHeight F 90 L wallDepth F 90 L] 2 times
-      SetPen
-      Home
+          90 U
+          PenDown
+          [wallHeight F 90 L wallDepth F 90 L] 2 times
+          SetPen
+          Home
 
-      [ 1 to k k / [dup F] k times drop ] to ff
-      [ 2 / dup R 0 F R 0 F ] to rr
+          #t SetMiter
+          ; #t SetSmooth
 
-      PenDown
-      1 ff 90 rr 1 ff 90 rr 1 ff 90 rr 1 ff 90 rr
-      PenUp
-    ]>>>>>
+          ; quote F to ff
+          [ 1 to k k / [dup F] k times drop ] to ff
+
+          [ R 0 F ] to rr
+          ; [ R 0 F 60 D ] to rr
+          ; [ 4 to k k / [dup R 0 F] k times drop ] to rr
+
+          PenDown
+          60 to sides
+          [4 sides / ff 360 sides / rr] sides 2 / 2 - times
+          1 0.5 1 PenScale 0 F
+          [4 sides / ff 360 sides / rr] 4 times
+          1 1 1 PenScale 0 F
+          [4 sides / ff 360 sides / rr] sides 2 / 2 - times
+          PenUp
+        ]>>
+       <mesh <box>>
+     ]>>>>>>
 
 ; <Exit "y" "lobby">
 ; <sprite "y" []
diff --git a/src/turtle.ts b/src/turtle.ts
index d22c5bb..0f20f9f 100644
--- a/src/turtle.ts
+++ b/src/turtle.ts
@@ -14,6 +14,8 @@ import * as Cat from './cat.js';
 export class PenState {
     templatePath: Vector3[] = [new Vector3()];
     paths: Vector3[][] | null = null;
+    directions: Quaternion[] | null = null;
+    templateScale = new Vector3(1, 1, 1);
 
     get isDown(): boolean {
         return this.paths !== null;
@@ -22,27 +24,43 @@ export class PenState {
     clear() {
         this.templatePath = [new Vector3()];
         this.paths = null;
+        this.directions = null;
     }
 
     set() {
         if (!this.paths) throw new Error("Cannot set pen with no paths");
         this.templatePath = this.paths[0];
         this.paths = null;
+        this.directions = null;
     }
 
     down() {
         this.paths = this.templatePath.map(_p => []);
+        this.directions = [];
     }
 
-    push(pos: Vector3, q: Quaternion) {
+    push(pos: Vector3, q: Quaternion, miter: boolean) {
+        const directions = this.directions!;
+        const paths = this.paths!;
+
+        if (miter && directions.length > 0) {
+            const lastQ = directions[directions.length - 1];
+            const lastDir = new Vector3(0, 0, 1).applyRotationQuaternionInPlace(lastQ);
+            const thisDir = new Vector3(0, 0, 1).applyRotationQuaternionInPlace(q);
+            const miterDir = lastDir.add(thisDir).normalize();
+            const miterPlane = Plane.FromPositionAndNormal(pos, miterDir);
+            for (let pathIndex = 0; pathIndex < paths.length; pathIndex++) {
+                const steps = paths[pathIndex];
+                const p = steps[steps.length - 1];
+                steps[steps.length - 1] = p.add(lastDir.scale(new Ray(p, lastDir).intersectsPlane(miterPlane)!));
+            }
+        }
+
         this.templatePath.forEach((p, i) => {
-            const r = new Vector3();
-            // p.multiplyToRef(this.templateScale, r);
-            // r.rotateByQuaternionToRef(q, r);
-            p.rotateByQuaternionToRef(q, r);
-            r.addInPlace(pos);
-            this.paths![i].push(r);
+            paths[i].push(p.multiply(this.templateScale).applyRotationQuaternion(q).addInPlace(pos));
         });
+
+        directions.push(q);
     }
 };
 
@@ -58,8 +76,8 @@ export class TurtleVM extends Cat.VM<TurtleVM> {
     pen = new PenState();
     pos = new Vector3();
     q = new Quaternion();
-    prevQ = this.q;
     smooth = false;
+    miter = false;
 
     get euler(): Vector3 {
         return this.q.toEulerAngles();
@@ -75,33 +93,24 @@ export class TurtleVM extends Cat.VM<TurtleVM> {
     }
 
     forwardBy(dist: number) {
-        const v = new Vector3(0, 0, dist);
-        v.rotateByQuaternionToRef(this.q, v);
+        const v = new Vector3(0, 0, dist).applyRotationQuaternionInPlace(this.q);
         this.pos.addInPlace(v);
-        if (this.pen.isDown) this.pen.push(this.pos, this.q);
-    }
-
-    setQ(newQ: Quaternion) {
-        this.q = newQ;
-    }
-
-    resetQ(newQ: Quaternion) {
-        this.q = this.prevQ = newQ;
+        if (this.pen.isDown) this.pen.push(this.pos, this.q, dist === 0.0 && this.miter);
     }
 
     rotate(y: number, x: number, z: number) {
         const e = this.euler;
         e.addInPlaceFromFloats(x * D2R, y * D2R, z * D2R);
-        this.setQ(e.toQuaternion());
+        this.q = e.toQuaternion();
     }
 
     relativeRotate(y: number, x: number, z: number) {
-        this.setQ(this.q.multiply(Quaternion.FromEulerAngles(x * D2R, y * D2R, z * D2R)));
+        this.q = this.q.multiply(Quaternion.FromEulerAngles(x * D2R, y * D2R, z * D2R));
     }
 
     penDown() {
         this.pen.down();
-        this.pen.push(this.pos, this.q);
+        this.pen.push(this.pos, this.q, false);
     }
 
     penUp(close: boolean) {
@@ -201,7 +210,7 @@ export class TurtleVM extends Cat.VM<TurtleVM> {
 }
 
 export const TurtlePrimitives: Cat.Environment<TurtleVM> = Object.assign({}, Cat.Primitives, {
-    'Home'() { this.pos = new Vector3(); this.resetQ(new Quaternion()); return []; },
+    'Home'() { this.pos = new Vector3(); this.q = new Quaternion(); return []; },
 
     'GetPos'() { return [this.pos.asArray()]; },
     'GetX'() { return [this.pos.x]; },
@@ -223,7 +232,7 @@ export const TurtlePrimitives: Cat.Environment<TurtleVM> = Object.assign({}, Cat
     'SetRY'(v) { this.q.y = v as number * D2R; return []; },
     'SetRZ'(v) { this.q.z = v as number * D2R; return []; },
     'SetHeading'(x, y, z) {
-        this.resetQ(Quaternion.FromEulerAngles(x as number * D2R, y as number * D2R, z as number * D2R));
+        this.q = Quaternion.FromEulerAngles(x as number * D2R, y as number * D2R, z as number * D2R);
         return [];
     },
 
@@ -244,11 +253,16 @@ export const TurtlePrimitives: Cat.Environment<TurtleVM> = Object.assign({}, Cat
     'ClearPen'() { this.pen.clear(); return []; },
     'SetPen'() { this.pen.set(); return []; },
 
+    'PenScale'(sx, sy, sz) {
+        this.pen.templateScale = new Vector3(sx as number, sy as number, sz as number);
+        return [];
+    },
     'PenDown'() { this.penDown(); return []; },
     'PenUp'() { this.penUp(false); return []; },
     'Close'() { this.penUp(true); return []; },
 
     'SetSmooth'(b) { this.smooth = b as boolean; return []; },
+    'SetMiter'(b) { this.miter = b as boolean; return []; },
     'SetSideOrientation'(s) {
         switch (s) {
             case "default": this.sideOrientation = Mesh.DEFAULTSIDE; break;