There is one constant in all those comment threads: FreeCAD. I don’t know if these suggestions reflect the popularity or difficulty of FreeCAD nevermind, it’s totally the difficulty.
[Brodie Fairhall] has a nice video about how to use parameters in FreeCAD. The nice thing about parameters is they don’t have to be just constants. You can put in formulae as well. For example ...
One all-in-one option is FreeCAD; CAD stands for Computer Aided Design. It's a free software package that can create and build 3D objects. By contrast, Cura is a free 3D "slicer" program that converts ...