How to prepare a 3D model for printing (STL, STEP, 3MF)
A practical guide to preparing a 3D model for custom printing — file formats, tolerances, wall thickness and the most common mistakes to avoid.
A quality print starts with a good model. Whether you create the model yourself or receive it from a supplier, it pays to know a few basic rules. You'll save both time and money.
Which file formats to send
- STL — the most widespread format for 3D printing (a mesh of triangles).
- STEP / STP — a parametric format, ideal for precise technical parts.
- 3MF — a more modern format that also carries colours and other information.
If you have a choice, STEP is best for technical parts because it preserves the exact geometry.
What to keep in mind during design
- Wall thickness — walls that are too thin may not print. Stick to at least 1–2 mm depending on the technology.
- Tolerances — for parts that fit together, allow for a small clearance.
- Overhangs — with FDM they need supports; SLS doesn't require them.
- Orientation — it affects both strength and surface quality.
The most common mistakes
- An unclosed ("leaky") mesh — the model isn't watertight.
- Flipped face normals.
- Details that are too small for the technology to hold.
We can fix most of these problems for you. If you don't have a model at all, we'll design it from a drawing, a photo or a sample — see our 3D modeling service.
Not sure whether your model is ready? Send it to us and we'll check it before quoting.