STL files are editable. An STL file contains 3D designs that you can edit in a 3D CAD application that supports the format. You can try software like Wings 3D, Autodesk Meshmixer, or MeshLab as ...

An imported STEP file is converted to a triangle mesh on import (making it much like a typical .stl or .3mf file) which means that slicing all happens as one would normally expect.

MF, an  XML-based data format developed by the 3MF Consortium, has officially become an ISO standard: ISO/IEC 25422:2025.