Doesn't have all the functionality that AutoCAD does, and there are some usability issues if you're really comfortable in AutoCAD already, but I imagine FreeCAD [0] would work well for your use case.
Blender allows for the use of human units. It also contains engines for physics and lots of videos explaining how to do interesting things, including allowing for Python scripting
Choosing a very popular free platform has benefits (blender.org)
Sileni|7 years ago
[0]: https://www.freecadweb.org/
acidburnNSA|7 years ago
[1] https://www.freecadweb.org/wiki/BIM_Workbench
trentlott|7 years ago
Choosing a very popular free platform has benefits (blender.org)
sanbor|7 years ago
LeonM|7 years ago
[0] https://www.sketchup.com/