Jewellery CAD file formats explained: .3dm, .stl, .step and .obj
A jewellery CAD model can be saved in several formats, and each one is made for a different job. Sending the wrong one can cause delays, so it helps to know the main four.
.3dm: the working file
This is Rhino's own format. It keeps the model as smooth, accurate surfaces and can be edited later. It is the best file to keep for yourself, because it can be changed and reused.
.stl: the printing file
An .stl file describes the model as a mesh of small triangles. It is the standard format for 3D printers. It does not store colours or materials, and it cannot be edited as easily, so it is made from the .3dm file for printing.
.step and .iges: exchange formats
These are neutral formats for moving a precise model between different CAD programs. They are less common in jewellery, but useful when a client uses other software.
.obj: a mesh for visuals
.obj is another mesh format, often used for 3D visuals and some rendering workflows rather than for production.
Which one should you send?
| You need | Send |
|---|---|
| To edit or reuse the design | .3dm |
| To print or cast | .stl |
| To open it in other CAD software | .step |
| To render it | .3dm (other formats may cost extra) |
We deliver .3dm and .stl files. See the casting-ready checklist for what else to check.
Frequently asked questions
Can I convert an .stl back to an editable model?
Not cleanly. An .stl is a mesh, so it is much harder to edit than the original .3dm. Always keep the .3dm.
Which units should the file use?
Millimetres. Always confirm the units, because a file in inches will print at the wrong size.
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