I created a model with three intersecting solids and exported as STL for my 3D printer.

I forgot to Boolean the model into a single solid, yet the STL file seems to be one piece, which is a good thing.

Does STL export by definition unify all intersecting parts?

Hi ed, the STL export itself does not do any intersections or boolean operations. If it was handled ok by your 3D printer, then that probably means your 3D printer software is able to tolerate intersecting volumes at least to a certain extent. I'm not so sure it would be good to rely on that all the time though, probably some kinds of arrangements are likely to be more difficult for it to handle like if the are any coincident edges between parts.

- Michael

Thanks Michael. I did some testing - My slicer program definitely treats intersecting solids as one solid if they are imported together. If imported one at a time, it treats as 3 models.

You're right, it would be safer to Boolean union in MoI first (When I remember to do so :)