A file with .stl extension is a 3D graphic file native to Stereolithography technology. Stereolithography is basically a type of 3D printing technology to create 3D models. What is an STL file?

STL — short for stereolithography — is a simple format that just holds a bunch of triangles. If you need any information about the part — like colors or materials. Worse still, as in our hypothetical ...

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.