.3mf

What is a .3mf file?

3MF is a modern 3D printing format replacing STL — supporting colour, materials, textures, and multiple objects in one file.

Safe format
Type Cad
By 3MF Consortium
MIME application/vnd.ms-package.3dmanufacturing-3dmodel+xml

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What is it

You're preparing a 3D print and the slicer is asking for a file. If you have a 3MF, you're ahead of the curve. 3MF (3D Manufacturing Format) was designed to replace STL with everything STL can't do — colour, materials, textures, multiple objects, print settings, and thumbnails, all in a single file.

3MF is backed by a consortium including Microsoft, HP, Autodesk, Stratasys, and Ultimaker. Under the hood it's a ZIP archive containing XML and texture files — open one with a ZIP tool if you're curious. The format solves real STL problems: it can't have non-manifold geometry (holes in the mesh), it carries unit information (no more "is this millimetres or inches?"), and it embeds print settings like infill and support configuration.

Cura, PrusaSlicer, BambuStudio, and Windows 3D Builder all support 3MF natively. If your CAD software exports 3MF, prefer it over STL. If your print service only accepts STL, most slicers can convert. 3MF is what STL would be if it were invented today instead of 1987.

Technical details
Full Name
3D Manufacturing Format
MIME Type
application/vnd.ms-package.3dmanufacturing-3dmodel+xml
Developer
3MF Consortium
Magic Bytes
50 4B 03 04
Safety
.3mf is a known, safe format.
What opens it
Cura
FREE All
PrusaSlicer
FREE All
Windows 3D Builder
FREE Windows
FAQ
Should I use 3MF or STL for 3D printing?
Use 3MF if your slicer and workflow support it — it carries more information and prevents common mesh errors. Use STL if your print service or slicer requires it. Most modern slicers handle both.
What's inside a 3MF file?
A 3MF file is actually a ZIP archive containing XML files describing geometry, materials, and print settings, plus optional texture images. Rename one to .zip and explore its contents with any archive tool.
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