Which file do you need for 3D printing: STL, STEP or 3MF?
If you have a CAD model, send us the STEP file: it is the most accurate and lets us correct the part if needed. STL is fine when the model is final. If you have no file at all, a sketch, a few photos and the main measurements are enough.
The formats compared
| Format | What it contains | When to use it |
|---|---|---|
| STEP (.step, .stp) | The exact CAD geometry, with surfaces and dimensions | When the part may need changes or dimensional checks |
| STL (.stl) | The part's surface approximated with triangles, with no units | When the model is final and only needs printing |
| 3MF (.3mf) | Like STL, but with units, several parts in one file and orientation | When you have several parts to print together or want to show how to lay them out |
| OBJ (.obj) | A triangle surface, often from graphics and scanning software | When the model comes from a 3D scan or a free-form modelling program |
Why we prefer STEP
STEP keeps the true shape of the part: a hole stays a circle, a flat surface stays flat. That way we can fix a wall that is too thin, add a fillet or adapt a joint for 3D printing without redrawing everything. With an STL these corrections are slower and less precise.
How to export a good STL
- Units in millimetres: STL does not store units, so a part modelled in inches or metres arrives at the wrong size.
- Sensible resolution: too coarse a tolerance makes curves faceted; too fine creates heavy files with no benefit.
- One file per part: if the assembly has several components, export them separately or use a 3MF.
- Closed surface: the model must be a solid with no holes in its surface, otherwise it needs repairing before printing.
If you have no 3D file
Many requests start without a model. We need:
- a sketch or drawing, even by hand, with the main dimensions;
- a few photos of the part to replace, with a ruler or tape measure next to it;
- where it is mounted and what loads it must take.
From there our product design service prepares the 3D model, which we send you for approval before printing.
How to send us your files
The quote form accepts STL, STEP, 3MF, OBJ, ZIP, PDF and images, up to 10 MB. If you have several files or a large one, put them in a ZIP archive. In your request, tell us how many parts you need and, if you already know, the material: otherwise we recommend it based on the use, as explained in our materials guide.
Frequently asked questions
Can I send a DWG file or a 2D PDF?
Yes, as a reference: export the drawing as PDF or put the DWG in a ZIP archive. From a dimensioned 2D drawing we rebuild the 3D model; the modelling time is included in the quote.
My supplier's file is in a native format (SolidWorks, Inventor, Fusion). Is that a problem?
If you can, export it as STEP: every CAD program reads it and it keeps full precision.
My STL has errors. Can you still print it?
Usually, yes. We check every file before printing and, if there are holes or flipped surfaces, we repair it or ask you for a new export.
Does the file affect the price?
The format does not, the work does: if the model needs correcting or rebuilding, we show it in the quote. For the other factors, read our guide on how much a prototype costs.
Can I send a 3D scan?
Yes, as STL or OBJ. Scans often have uneven surfaces: we clean them up and, where precise dimensions matter, rebuild the mating features in CAD.
Tell us about the part you need.
Attach the file if you have one, or describe the part with photos and measurements. We reply within 24 working hours with a quote or the technical questions we need answered.
Request a quote