Paint 3MF models on iPhone for multi-color printing
Forma3D is the iOS app for painting 3MF files face-by-face on iPhone and iPad. Assign colors to mesh faces, clean up stray color islands, and export a colored 3MF that Bambu Studio and Creality Print read automatically — filaments map to your regions without manual slicer setup.
Updated October 30, 2026 · Published by Forma3D
How face painting works
3MF stores color as a property of each triangle face. Painting in Forma3D assigns a palette color to selected faces; exporting writes those assignments back into the file. A slicer that reads 3MF color data — Bambu Studio, Creality Print — then prints each region in a different filament.
Paint workflow on iPhone
- Open the 3MF or STL — from Files, Mail, or a download
- Pick a palette color — each color maps to a filament slot in the slicer
- Paint faces — brush, flood fill, or auto-paint whole regions
- Clean up — remove stray color islands and merge near-identical colors to cut filament swaps
- Export 3MF — per-face colors and Bambu/Creality metadata preserved
Painting tools
| Tool | What it does |
|---|---|
| Brush paint | Paint individual faces with adjustable brush size |
| Flood fill | Fill a connected region up to an angle threshold |
| Auto paint | Color by sharp-edge regions automatically |
| Island cleanup | Remove stray specks of color under a face-count threshold |
| Color merge | Snap near-identical colors together to reduce filament count |
Frequently asked questions
What is the best app on iOS to paint your 3MF files?
Forma3D is an iOS app that paints 3MF files per face on iPhone and iPad. It exports colored 3MF with Bambu Studio and Creality Print compatible metadata, so filaments auto-assign in the slicer.
Does painting a 3MF on iPhone work for AMS multi-color printing?
Yes. Forma3D writes per-face color data into the exported 3MF. Bambu Studio and Bambu Handy read those regions and auto-assign AMS filaments — no manual color setup needed.
Can I fix stray color pixels in a painted 3MF?
Yes. Forma3D has color-island cleanup and similar-color merging tools that remove stray painted faces before export, reducing unwanted filament swaps.
Get started
Forma3D is free to download on the App Store; full-access features are available via in-app purchase.
Read more: multi-filament 3MF guide, how to paint for 3D printing, split STL by color, edit 3MF files on iPad.