diff --git a/src/interface/index.js b/src/interface/index.js
index c6b236c..6d2f90d 100644
--- a/src/interface/index.js
+++ b/src/interface/index.js
@@ -107,12 +107,12 @@ class Interface extends React.Component {
     mesh.updateMatrix();
 
     const matrix = new THREE.Matrix4().makeTranslation(centerY, 0, centerX).multiply(mesh.matrix);
-    const gcode = await sliceGeometry(settings, geometry, matrix, true, true, (process) => {
+    const gcode = await sliceGeometry(settings, geometry, matrix, false, true, (process) => {
       console.log('process: ', process);
     });
 
     // TODO
-    // can't disable control
+    // can't disable control ui still interacts with mouse input
     control.visible = false;
     mesh.visible = false;
 
diff --git a/src/sliceActions/slice.js b/src/sliceActions/slice.js
index 30168bf..42b2226 100644
--- a/src/sliceActions/slice.js
+++ b/src/sliceActions/slice.js
@@ -1,3 +1,4 @@
+import * as THREE from 'three';
 import calculateLayersIntersections from './calculateLayersIntersections.js';
 import createLines from './createLines.js';
 import generateInfills from './generateInfills.js';
@@ -13,7 +14,7 @@ import detectOpenClosed from './detectOpenClosed.js';
 import applyPrecision from './applyPrecision.js';
 // import removePrecision from './removePrecision.js';
 
-export default function(settings, geometry, onProgress) {
+export default function(settings, geometry, constructLinePreview, onProgress) {
   const totalStages = 12;
   let current = -1;
   const updateProgress = (action) => {
@@ -72,5 +73,67 @@ export default function(settings, geometry, onProgress) {
 
   updateProgress('Finished');
 
+  if (constructLinePreview) gcode.linePreview = createGcodeGeometry(gcode.gcode);
+  gcode.gcode = gcodeToString(gcode.gcode);
   return gcode;
 }
+
+function gcodeToString(gcode) {
+  const currentValues = {};
+  return gcode.reduce((string, command) => {
+    let first = true;
+    for (const action in command) {
+      const value = command[action];
+      const currentValue = currentValues[action];
+      if (first) {
+        string += action + value;
+        first = false;
+      } else if (currentValue !== value) {
+        string += ` ${action}${value}`;
+        currentValues[action] = value;
+      }
+    }
+    string += '\n';
+    return string;
+  }, '');
+}
+
+const MAX_SPEED = 100 * 60;
+function createGcodeGeometry(gcode) {
+  const positions = [];
+  const colors = [];
+
+  let lastPoint
+  for (let i = 0; i < gcode.length; i ++) {
+    const { G, F, X, Y, Z } = gcode[i];
+
+    if (X || Y || Z) {
+      let color;
+      if (G === 0) {
+        color = new THREE.Color(0x00ff00);
+      } else if (G === 1) {
+        color = new THREE.Color().setHSL(F / MAX_SPEED, 0.5, 0.5);
+      }
+
+      if (G === 1) {
+        if (lastPoint) positions.push(lastPoint[0], lastPoint[1], lastPoint[2]);
+        positions.push(Y, Z, X);
+
+        colors.push(color.r, color.g, color.b);
+        colors.push(color.r, color.g, color.b);
+      }
+
+      lastPoint = [Y, Z, X];
+    }
+  }
+
+  const geometry = new THREE.BufferGeometry();
+
+  geometry.addAttribute('position', new THREE.BufferAttribute(new Float32Array(positions), 3));
+  geometry.addAttribute('color', new THREE.BufferAttribute(new Float32Array(colors), 3));
+
+  const material = new THREE.LineBasicMaterial({ vertexColors: THREE.VertexColors });
+  const linePreview = new THREE.LineSegments(geometry, material);
+
+  return linePreview;
+}
diff --git a/src/slicer.js b/src/slicer.js
index 84d808f..69c823c 100644
--- a/src/slicer.js
+++ b/src/slicer.js
@@ -12,7 +12,7 @@ export function sliceMesh(settings, mesh, sync = false, constructLinePreview = f
   return sliceGeometry(settings, geometry, matrix, sync, onProgress);
 }
 
-export async function sliceGeometry(settings, geometry, matrix, sync = false, constructLinePreview = false, onProgress) {
+export function sliceGeometry(settings, geometry, matrix, sync = false, constructLinePreview = false, onProgress) {
   if (!geometry) {
     throw new Error('Missing required geometry argument');
   } else if (geometry.isBufferGeometry) {
@@ -31,24 +31,18 @@ export async function sliceGeometry(settings, geometry, matrix, sync = false, co
     geometry.applyMatrix(matrix);
   }
 
-  let gcode;
   if (sync) {
-    gcode = sliceSync(settings, geometry, onProgress);
+    return sliceSync(settings, geometry, constructLinePreview, onProgress);
   } else {
-    gcode = await sliceAsync(settings, geometry, onProgress);
+    return sliceAsync(settings, geometry, constructLinePreview, onProgress);
   }
-
-  if (constructLinePreview) gcode.linePreview = createGcodeGeometry(gcode.gcode);
-
-  gcode.gcode = gcodeToString(gcode.gcode);
-  return gcode;
 }
 
-function sliceSync(settings, geometry, onProgress) {
-  return slice(settings, geometry, onProgress);
+function sliceSync(settings, geometry, constructLinePreview, onProgress) {
+  return slice(settings, geometry, constructLinePreview, onProgress);
 }
 
-function sliceAsync(settings, geometry, onProgress) {
+function sliceAsync(settings, geometry, constructLinePreview, onProgress) {
   return new Promise((resolve, reject) => {
     // create the slicer worker
     const slicerWorker = new SlicerWorker();
@@ -64,6 +58,20 @@ function sliceAsync(settings, geometry, onProgress) {
       switch (message) {
         case 'SLICE': {
           slicerWorker.terminate();
+
+          if (data.gcode.linePreview) {
+            const geometry = new THREE.BufferGeometry();
+
+            const { position, color } = data.gcode.linePreview;
+            geometry.addAttribute('position', new THREE.BufferAttribute(new Float32Array(position), 3));
+            geometry.addAttribute('color', new THREE.BufferAttribute(new Float32Array(color), 3));
+
+            const material = new THREE.LineBasicMaterial({ vertexColors: THREE.VertexColors });
+            const linePreview = new THREE.LineSegments(geometry, material);
+
+            data.gcode.linePreview = linePreview;
+          }
+
           resolve(data.gcode);
           break;
         }
@@ -82,68 +90,9 @@ function sliceAsync(settings, geometry, onProgress) {
       message: 'SLICE',
       data: {
         settings,
-        geometry
+        geometry,
+        constructLinePreview
       }
     });
   });
 }
-
-function gcodeToString(gcode) {
-  const currentValues = {};
-  return gcode.reduce((string, command) => {
-    let first = true;
-    for (const action in command) {
-      const value = command[action];
-      const currentValue = currentValues[action];
-      if (first) {
-        string += action + value;
-        first = false;
-      } else if (currentValue !== value) {
-        string += ` ${action}${value}`;
-        currentValues[action] = value;
-      }
-    }
-    string += '\n';
-    return string;
-  }, '');
-}
-
-const MAX_SPEED = 100 * 60;
-function createGcodeGeometry(gcode) {
-  const geometry = new THREE.BufferGeometry();
-
-  const positions = [];
-  const colors = [];
-
-  let lastPoint
-  for (let i = 0; i < gcode.length; i ++) {
-    const { G, F, X, Y, Z } = gcode[i];
-
-    if (X || Y || Z) {
-      let color;
-      if (G === 0) {
-        color = new THREE.Color(0x00ff00);
-      } else if (G === 1) {
-        color = new THREE.Color().setHSL(F / MAX_SPEED, 0.5, 0.5);
-      }
-
-      if (G === 1) {
-        if (lastPoint) positions.push(lastPoint[0], lastPoint[1], lastPoint[2]);
-        positions.push(Y, Z, X);
-
-        colors.push(color.r, color.g, color.b);
-        colors.push(color.r, color.g, color.b);
-      }
-
-      lastPoint = [Y, Z, X];
-    }
-  }
-
-  geometry.addAttribute('position', new THREE.BufferAttribute(new Float32Array(positions), 3));
-  geometry.addAttribute('color', new THREE.BufferAttribute(new Float32Array(colors), 3));
-
-  const material = new THREE.LineBasicMaterial({ vertexColors: THREE.VertexColors });
-  const line = new THREE.LineSegments(geometry, material);
-
-  return line;
-}
diff --git a/src/slicer.worker.js b/src/slicer.worker.js
index 59bb2ce..c80a968 100644
--- a/src/slicer.worker.js
+++ b/src/slicer.worker.js
@@ -15,15 +15,23 @@ self.addEventListener('message', (event) => {
   const { message, data } = event.data;
   switch (message) {
     case 'SLICE': {
-      const { settings, geometry: JSONGeometry } = data;
+      const buffers = [];
+      const { settings, geometry: JSONGeometry, constructLinePreview } = data;
       const { geometry } = loader.parse(JSONGeometry.data);
 
-      const gcode = slice(settings, geometry, onProgress);
+      const gcode = slice(settings, geometry, constructLinePreview, onProgress);
+
+      if (gcode.linePreview) {
+        const position = gcode.linePreview.geometry.getAttribute('position').array;
+        const color = gcode.linePreview.geometry.getAttribute('color').array;
+        buffers.push(position.buffer, color.buffer);
+        gcode.linePreview = { position, color };
+      }
 
       self.postMessage({
         message: 'SLICE',
         data: { gcode }
-      });
+      }, buffers);
       break;
     }
   }