Is it worth moving your STL library to 3MF?
The newer slicers save everything as 3MF. The mesh is the same; what changes is everything around it.
Anyone who has printed for a few years has a folder full of STL files. The newer slicers save everything as 3MF. Is it worth converting the library? It depends on what you want to keep.
What 3MF keeps that STL loses
- The unit. 3MF says "millimetre". STL says nothing, which is where the part that shows up tiny in the slicer comes from.
- Several objects. A project with 6 parts lives in one file, each with a name and a position on the plate.
- Colour and painting. Painting done in Bambu Studio or OrcaSlicer lives in the 3MF. In STL it is gone.
- Slicer settings. Layer height, infill, supports, filament profile. Opening the 3MF reopens the project as you left it.
- Compression. It is a zip inside: the same part takes a fraction of a text STL.
What does not improve
The mesh is the same. Converting STL to 3MF does not make curves smoother or fix holes: if the STL has an error, the 3MF has the same error. That is what repair is for, before any conversion.
How to convert in bulk
No tool needed: drag the STL files into Bambu Studio, OrcaSlicer or PrusaSlicer and save as a project (.3mf). For dozens of files, PrusaSlicer has a command-line mode that exports them one by one.
Worth it for what
- Projects you reopen: yes. Keep them as 3MF with the settings.
- Models you publish or send to a print service: keep the STL alongside. It is what everyone opens.
- Two-colour models for a single-nozzle printer: the painted 3MF can become one solid part per colour, with a socket, no AMS needed.
And the reverse path. When a Bambu 3MF has to become STL (for an older slicer or a print service), use a converter that reads the "production" extension, or it comes out empty.
