Things are starting to get exciting over at FreeCAD. In the words of the developers:
FreeCAD is a general purpose Open Source 3D CAD/MCAD/CAx/CAE/PLM modeler, aimed directly at mechanical engineering and product design but also fits a wider range of uses in engineering, such as architecture or other engineering specialties. It is a feature-based parametric modeler with a modular software architecture which makes it easy to provide additional functionality without modifying the core system.
What’s really interesting is that FreeCAD now has a functional constraints-based Sketcher and Part Design Workbench. So now you can sketch a profile, add dimensions and constraints, then extrude or revolve that profile into a solid. The resulting solid is fully parametric, meaning that you can go back and change the sketch or any of the dimensions at any point and the whole model will update automatically. This is a very different approach than Sketchup takes, and is the same way Solidworks does things.[^1]
Also of note is that I’ve finally managed to build FreeCAD into a single application bundle, so no more installer! There are some caveats[^2], but they should be worked out soon.
Download the latest Mac version from the FreeCAD site.
[^1]: Not to say that FreeCAD is even close to feature-parity with Solidworks, but this is a big step in that direction.
[^2]: Specifically, Pivy is missing so the Draft Workbench isn’t working. Also, the application is huge at over 1 GB.