diff --git a/src/components/ExportButton.tsx b/src/components/ExportButton.tsx
index fe4b8db..0a39cd5 100644
--- a/src/components/ExportButton.tsx
+++ b/src/components/ExportButton.tsx
@@ -30,25 +30,32 @@ export default function ExportButton({className, style}: {className?: string, st
       ] : [
         {
           data: 'glb',
-          buttonLabel: 'GLB',
+          buttonLabel: 'Download GLB',
           label: 'GLB (binary glTF)',
           icon: 'pi pi-file',
           command: () => model!.setFormats(undefined, 'glb'),
         },
         {
           data: 'stl',
-          buttonLabel: 'STL',
+          buttonLabel: 'Download STL',
           label: 'STL (binary)',
           icon: 'pi pi-file',
           command: () => model!.setFormats(undefined, 'stl'),
         },
         {
           data: 'off',
-          buttonLabel: 'OFF',
+          buttonLabel: 'Download OFF',
           label: 'OFF (Object File Format)',
           icon: 'pi pi-file',
           command: () => model!.setFormats(undefined, 'off'),
         },
+        {
+          data: '3mf',
+          buttonLabel: 'Download 3MF',
+          label: '3MF (3D Manufacturing Format)',
+          icon: 'pi pi-file',
+          command: () => model!.setFormats(undefined, '3mf'),
+        },
       ];
 
     const exportFormat = state.is2D ? state.params.exportFormat2D : state.params.exportFormat3D;
diff --git a/src/components/Footer.tsx b/src/components/Footer.tsx
index 61a34ed..b6c022f 100644
--- a/src/components/Footer.tsx
+++ b/src/components/Footer.tsx
@@ -6,7 +6,6 @@ import * as monaco from 'monaco-editor/esm/vs/editor/editor.api';
 import { Button } from 'primereact/button';
 import { ProgressBar } from 'primereact/progressbar';
 import { Badge } from 'primereact/badge';
-import { Menu } from 'primereact/menu';
 import { Toast } from 'primereact/toast';
 import HelpMenu from './HelpMenu';
 import ExportButton from './ExportButton';
@@ -53,14 +52,35 @@ export default function Footer({style}: {style?: CSSProperties}) {
         margin: '5px',
         ...(style ?? {})
     }}>
-      <Button
+      {state.output && !state.output.isPreview
+        ? (
+            <ExportButton />
+        ) : state.previewing ? (
+          <Button
+            icon="pi pi-bolt"
+            disabled
+            className="p-button-sm"
+            label="Previewing..."
+            />
+        ) : state.output && state.output.isPreview ? (
+            <Button
+              icon="pi pi-bolt"
+              onClick={() => model.render({isPreview: false, now: true})}
+              className="p-button-sm"
+              disabled={state.rendering}
+              label={state.rendering ? 'Rendering...' : 'Render'}
+              />
+        ) : undefined
+      }
+      {/* <RenderExportButton /> */}
+      {/* <Button
         icon="pi pi-bolt"
         onClick={() => model.render({isPreview: false, now: true})}
         className="p-button-sm"
         label="Render"
         />
 
-      <ExportButton />
+      <ExportButton /> */}
       
       {(state.lastCheckerRun || state.output) &&
         <Button type="button"
diff --git a/src/io/export_3mf.ts b/src/io/export_3mf.ts
index 2c5806f..e3e630d 100644
--- a/src/io/export_3mf.ts
+++ b/src/io/export_3mf.ts
@@ -35,13 +35,6 @@ export function exportOffTo3MF(data: IndexedPolyhedron, extruderColors?: chroma.
         getColorMapping(data.colors.map(c => chroma.rgb(...c)), extruderColors).map(i => PAINT_COLOR_MAP[i]);
     
     const archive = {
-        // _rels/.rels
-        '[Content Types].xml': new TextEncoder().encode([
-            '<?xml version="1.0" encoding="utf-8"?>',
-            '<Types xmlns="http://schemas.openxmlformats.org/package/2006/content-types">',
-                '<Default Extension="model" ContentType="application/vnd.ms-package.3dmanufacturing-3dmodel+xml"/>',
-            '</Types>',
-        ].join('\n')),
         '3D/3dmodel.model': new TextEncoder().encode([
             '<?xml version="1.0" encoding="utf-8"?>',
             '<model unit="millimeter" xml:lang="en-US" xmlns="http://schemas.microsoft.com/3dmanufacturing/core/2015/02" xmlns:p="http://schemas.microsoft.com/3dmanufacturing/production/2015/06">',
@@ -50,7 +43,7 @@ export function exportOffTo3MF(data: IndexedPolyhedron, extruderColors?: chroma.
                 '<meta name="slic3rpe:MmPaintingVersion" value="1"/>',
                 '<resources>',
                     '<basematerials id="2">',
-                    ...data.colors.map((color, i) => `<base name="color_${i}" displaycolor="#${chroma.rgb(...color).hex()}"/>`),
+                    ...data.colors.map((color, i) => `<base name="color_${i}" displaycolor="${chroma.rgb(...color).hex()}"/>`),
                     '</basematerials>',
                     `<object id="1" name="OpenSCAD Model" type="model" p:UUID="${objectUuid}" pid="2" pindex="0">`,
                         '<mesh>',
@@ -80,6 +73,18 @@ export function exportOffTo3MF(data: IndexedPolyhedron, extruderColors?: chroma.
                 '</build>',
             '</model>',
         ].join('\n')),
+        '[Content_Types].xml': new TextEncoder().encode([
+            '<?xml version="1.0" encoding="utf-8"?>',
+            '<Types xmlns="http://schemas.openxmlformats.org/package/2006/content-types">',
+                '<Default Extension="model" ContentType="application/vnd.ms-package.3dmanufacturing-3dmodel+xml"/>',
+            '</Types>',
+        ].join('\n')),
+        '_rels/.rels': new TextEncoder().encode([
+            '<?xml version="1.0" encoding="utf-8"?>',
+            '<Relationships xmlns="http://schemas.openxmlformats.org/package/2006/relationships">',
+            '<Relationship Type="http://schemas.microsoft.com/3dmanufacturing/2013/01/3dmodel" Target="/3D/3dmodel.model" Id="rel0"/>',
+            '</Relationships>',
+        ].join('\n')),
     };
     return new Blob([UZIP.encode(archive)], {type: 'model/3mf'});
 }
diff --git a/src/io/export_glb.ts b/src/io/export_glb.ts
index c16c01f..62f6d70 100644
--- a/src/io/export_glb.ts
+++ b/src/io/export_glb.ts
@@ -68,7 +68,7 @@ function getGeom(data: IndexedPolyhedron): Geom {
     };
 }
 
-export async function convertOffToGlb(data: IndexedPolyhedron, defaultColor: Color = DEFAULT_FACE_COLOR): Promise<Blob> {
+export async function exportGlb(data: IndexedPolyhedron, defaultColor: Color = DEFAULT_FACE_COLOR): Promise<Blob> {
     const doc = new Document();
     const lightExt = doc.createExtension(KHRLightsPunctual);
     const buffer = doc.createBuffer();
diff --git a/src/runner/actions.ts b/src/runner/actions.ts
index 805844b..5b58a7a 100644
--- a/src/runner/actions.ts
+++ b/src/runner/actions.ts
@@ -128,7 +128,7 @@ export const render =
     if (source.content == null) throw new Error('Source content is null!');
     const content = [...prefixLines, source.content].join('\n');
 
-    const actualRenderFormat = renderFormat == 'glb' ? 'off' : renderFormat;
+    const actualRenderFormat = renderFormat == 'glb' || renderFormat == '3mf' ? 'off' : renderFormat;
     const outFile = 'out.' + actualRenderFormat;
     const args = [
       scadPath,
diff --git a/src/state/model.ts b/src/state/model.ts
index bef56a4..3fd996a 100644
--- a/src/state/model.ts
+++ b/src/state/model.ts
@@ -10,7 +10,8 @@ import JSZip from 'jszip';
 import { ProcessStreams } from "../runner/openscad-runner";
 import { is2DFormatExtension } from "./formats";
 import { parseOff } from "../io/import_off";
-import { convertOffToGlb } from "../io/export_glb";
+import { exportGlb } from "../io/export_glb";
+import { exportOffTo3MF as export3MF } from "../io/export_3mf";
 
 export class Model {
   constructor(private fs: FS, public state: State, private setStateCallback?: (state: State) => void, 
@@ -212,37 +213,47 @@ export class Model {
       s.exporting = true;
     });
 
-    const outFile = this.state.output?.outFile;
-    const outFileURL = this.state.output?.outFileURL;
-    if (!outFile || !outFileURL) {
+    if (!this.state.output?.outFile || !this.state.output?.outFileURL) {
       throw new Error('No output file to export');
     }
 
-    const scadPath = '/export.scad'
-    const sources: Source[] = [
-      {
-        path: scadPath,
-        content: `import("${outFile.name}");`
-      },
-      {
-        path: outFile.name,
-        url: outFileURL,
-      }
-    ];
-    let {features, exportFormat2D, exportFormat3D} = this.state.params;
+    const {features, exportFormat2D, exportFormat3D} = this.state.params;
+    const exportFormat = this.state.is2D ? exportFormat2D : exportFormat3D;
 
-    const renderArgs: RenderArgs = {
-      mountArchives: false,
-      scadPath,
-      sources,
-      extraArgs: [], isPreview: false,
-      features,
-      renderFormat: this.state.is2D ? exportFormat2D : exportFormat3D,
-      streamsCallback: ps => console.log('Export', JSON.stringify(ps)),
-    };
-    
     try {
-      const output = await render(renderArgs)({now: true});
+      let output: RenderOutput;
+      if (exportFormat === '3mf') {
+        const start = performance.now();
+        const data = parseOff(await this.state.output.outFile.text());
+        const exportedData = export3MF(data);
+        const elapsedMillis = performance.now() - start;
+        output = {
+          outFile: new File([exportedData], this.state.output.outFile.name.replace('.off', '.3mf')),
+          elapsedMillis,
+          logText: '',
+          markers: [],
+        };
+      } else {
+        output = await render({
+          mountArchives: false,
+          scadPath: '/export.scad',
+          sources: [
+            {
+              path: '/export.scad',
+              content: `import("${this.state.output?.outFile.name}");`
+            },
+            {
+              path: this.state.output?.outFile.name,
+              url: this.state.output?.outFileURL,
+            }
+          ],
+          extraArgs: [], isPreview: false,
+          features,
+          renderFormat: exportFormat,
+          streamsCallback: ps => console.log('Export', JSON.stringify(ps)),
+        })({now: true});
+      }
+      
       const outFileURL = URL.createObjectURL(output.outFile);
       this.mutate(s => {
         s.exporting = false;
@@ -372,7 +383,7 @@ export class Model {
       }
       if (displayFile.name.endsWith('.off')) {
         const offData = parseOff(await displayFile.text());
-        displayFile = new File([await convertOffToGlb(offData)], displayFile.name.replace('.off', '.glb'));
+        displayFile = new File([await exportGlb(offData)], displayFile.name.replace('.off', '.glb'));
       }
       const outFileURL = URL.createObjectURL(output.outFile);
       const displayFileURL = displayFile && await readFileAsDataURL(displayFile);