[Brian_K_White]

You can do that effortlessly right in openscad itself or in freecad for a more visual way, or in every single cad app in existence I think.

In freecad you first just open the stl file, then Part -> Create part from mesh, then you have a solid you can modify.

[jandrese]

Sounds great in theory until you actually try it and discover that anytime a STL touches another object the F6 render craps out with "Manifold conversion failed: NotManifold"

[fogleman]

I just tried this in OpenSCAD and it crashed:

intersection() { import("3DBenchy.stl"); sphere(30); }

[bartvk]

FYI, I just tested this in OpenSCAD version 2025.09.13 and it works fine.

[fogleman]

Indeed it does. Looks like their recent dev builds are way better. Good to know.

[ajolly]

Yeah you definitely want to use the dev builds for openscad