Solvespace 

Solvespace is a parametric 3D CAD program with 2D sketching and modeling capabilities that I have been experimenting with given the eldritch horror that is and the lack of modern, local-only CAD tools.

It is still actively developed (although there have been no major releases in years) and available for Windows, macOS, and Linux. Its biggest shortcoming for me is the lack of fillet and chamfer features, which are essential for 3D printing. However, it is a great tool for creating parametric models and assemblies, and it has a simple and intuitive interface (if more than a bit dated).