Merge STL files into one
Drop several models at once, or add them one by one, and choose “Combine into one”: where they overlap they are joined into one solid surface, so the slicer sees a single clean model instead of shapes stacked inside each other.
Saves model files for your slicer, never printer code. Opened and sliced in PrusaSlicer, OrcaSlicer, Bambu Studio and Cura.
Joined, not stacked
Putting two STL files into one file is easy; the trouble is the walls left inside where they overlap, which slicers report as errors or print as extra perimeters. Combining computes one outside surface, so the inside walls are gone.
Or keep them apart in one file
To keep the models separate but in one file, skip combining and save as 3MF — each stays its own object, ready to arrange or to give its own colour in the slicer.
Lining them up
Each file keeps its own position from the program that made it. Models from the same project line up as they were designed; for others, move them with the arrows in the view or by exact numbers on Move, turn, or select two and press “Centre on model 1”.
Questions
- Can I subtract one model from another?
- Yes — that is its own page: the first one you select keeps its shape, the others are taken out of it.
- What if the files are broken?
- On this page they are repaired when you open them, so combining always starts from solid models.