Convert OBJ to 3MF — Multi-Color 3D Printing with Materials (Beta)
If you’re printing on a Bambu Lab with AMS, a Prusa with MMU, or sending to a print service like Shapeways — 3MF is what you want. Unlike [OBJ to STL](/convert/obj-to-stl) which strips all material data, this converter preserves your .mtl colors and textures in the 3MF package. Multi-color prints just work.
Last updated Mar 2026
Beta — 3MF support is experimental. Some models may not convert correctly.
Drag OBJ file here (with MTL & textures), or upload a ZIP
Supports .obj files (+ .mtl, textures, or .zip) up to 150MB
Usually under 3 seconds — depends on file size.
What You Should Know
What Changes During Conversion
Geometry (vertices and faces) is preserved. OBJ quads and n-gons are triangulated (3MF uses triangles). OBJ materials (.mtl diffuse colors, specular, and diffuse texture maps) are converted to 3MF material definitions and embedded in the OPC package. UV coordinates are preserved for texture-mapped models. The output is a .3mf file, which is actually a ZIP archive following the Open Packaging Conventions (OPC) specification — you can rename it to .zip and inspect the contents.
OPC Package Structure
3MF files use OPC (Open Packaging Conventions), the same packaging format as .docx and .xlsx files. Inside: /3D/3dmodel.model (XML geometry and materials), /Metadata/thumbnail.png (model preview), and /Textures/*.png (embedded textures). This self-contained structure eliminates the "missing texture" problem that plagues OBJ workflows — everything travels in one file.
OBJ vs 3MF: Quick Comparison
| Feature | OBJ | 3MF |
|---|---|---|
| Geometry | Polygons (quads, n-gons) | Triangles |
| Materials | Phong/Blinn (.mtl, external) | Embedded (OPC package) |
| Multi-Color Print | Not designed for printing | Native support |
| File Packaging | Loose files (.obj + .mtl + textures) | Single file (ZIP/OPC) |
| Standardization | De facto (Wavefront, 1992) | ISO/IEC 21067 |
| Slicer Support | Limited (geometry import) | Full (materials, settings) |
Use OBJ for modeling and DCC interchange. Use 3MF for 3D printing, especially when color, materials, or print metadata matter. 3MF is the recommended replacement for STL in modern printing workflows.
When to Convert OBJ to 3MF
Multi-Color 3D Printing
OBJ with materials converts to 3MF with per-material color assignments. Send to a multi-material printer (Bambu Lab AMS, Prusa MMU, Mosaic Palette) and print with accurate colors directly from the 3MF file. No manual color assignment in the slicer required.
Professional Print Service Submission
Print services (Shapeways, Sculpteo, i.materialise, JLCPCB) increasingly prefer or require 3MF over STL. Converting OBJ to 3MF before submission ensures your material and color intent is communicated to the print service, reducing back-and-forth about specifications.
Self-Contained Print Archives
Archive 3D print projects as 3MF instead of loose OBJ + MTL + texture files. The 3MF package contains everything needed to reproduce the print — geometry, materials, colors, textures, and optionally print settings — in a single file that any modern slicer can open.