FWIW, I crashed and burned with pretty much every 3D CAD tool I tried (though I did make it through the tutorial for Dune 3D which was a first), but OpenSCAD has been quite workable, and the development of a Python-enabled version:

https://pythonscad.org/

has allowed me to extend it to do things which would be quite difficult in other tools:

https://github.com/WillAdams/gcodepreview