A model that looks perfect on screen can still fail on the printer. The file format decides what information reaches the slicer, and the geometry inside it decides whether the print succeeds.
STL
The oldest and most widely supported format. STL describes only the surface, as a mesh of triangles — no colour, no materials and no units. Most slicers assume millimetres, so a model exported in the wrong unit arrives 10 or 1000 times too small or too large. Smooth curved surfaces need many triangles, so files can get large.
OBJ
OBJ stores geometry plus texture coordinates, with materials and colour kept in a companion MTL file and image textures. It has no units either. It is common for general 3D exchange and for full-colour printing workflows.
3MF
3MF is the modern format, created by an industry consortium for additive manufacturing. A 3MF file is a compressed package that keeps units, colours, materials, several objects and even print settings together in one file. Current slicers such as PrusaSlicer, Bambu Studio and Cura read it, and several use it for their project files.
Which one should you use?
| Format | Best for |
|---|---|
| STL | Single-colour prints and maximum compatibility with printers and services |
| OBJ | Colour and texture workflows, general 3D exchange |
| 3MF | Multi-part and multi-colour prints, keeping units and settings with the model |
What makes a model print-ready
- Watertight. The mesh is closed, with no holes; the slicer has to know what is inside and outside.
- Manifold. Every edge belongs to exactly two faces — no stray internal faces or zero-thickness walls.
- Correct normals. All faces point outward.
- Enough wall thickness. Walls must be thicker than the minimum for your printer and material — check the machine’s or service’s guideline, often around a millimetre or more.
- Right scale and units. Measure the model before export.
- Printable overhangs. Steep overhangs need supports, or a model designed to avoid them.
- Clearances for moving or assembled parts. Parts that fit together need a small gap, typically a few tenths of a millimetre depending on the process.
Have a model that won’t print? A print-ready file from your model starts at 2,500,000 Toman, and a print-ready model from references at 7,500,000 Toman. We deliver STL, OBJ or 3MF — see 3D print-ready models.
