Updated October 22, 2026
An STL is the shape of your part
STL is the most widely used format in 3D printing. It describes an object's surface with thousands of small triangles, as if you wrapped it in paper cut into tiny triangles. It only stores the shape: no colors or materials.
That's why, to print in two colors, our converters give you a 3MF with the base and relief already together (or two separate STLs), or tell you at what height to change filament.
What opens it
An STL doesn't go straight to the printer: first it goes through a program called a slicer, which cuts it into layers and generates the instructions for your printer. The most popular ones are free:
- Cura: one of the most widely used, works with a huge number of brands.
- PrusaSlicer: complete and very reliable.
- Bambu Studio: the one for Bambu Lab printers.
- OrcaSlicer: based on the previous ones, with lots of printer profiles.
- Many brands ship their own version (for example, Creality Print). Use the one your printer recommends.
From STL to part, step by step
- Open the STL in your slicer and check that the size is what you expect (our files come in millimeters).
- Choose the material and layer height (0.2 mm is a good start).
- Check the layer preview: that's where you can add color changes.
- Save the file it generates (usually .gcode or .3mf) and send it to your printer via USB, memory card or Wi-Fi.
STL and 3MF
3MF is a newer format that, besides the shape, can store colors, materials and print settings. Modern slicers (Bambu Studio, PrusaSlicer, Orca, Cura) open both. That's why our "2-color" file is a 3MF: it arrives with both parts together and in place. If someone shares a 3MF with you, open it just like an STL.
Frequently asked questions
Can I edit an STL?
Yes, with modeling programs like Tinkercad (free, in the browser) or Blender, although editing triangles is harder than designing from scratch. For things like QR codes, names or photos it's easier to generate a new one with our converters.
Why does my STL come out tiny or huge?
STL doesn't store the unit of measurement. Almost all programs assume millimeters; if someone exported it in inches or centimeters, scale it in the slicer.