I thought I'd upload the solid library I use when I design physical things like cases and enclosures for DIY electronics projects.
I've used MCAD quite a bit but ended up writing my own solid libraries for a few projects I was working on. Maybe they'll be useful for you too.
Included are 3 files (for now) that cover metric sized bolt generation, some of the more popular development boards, and a wide variety of battery types and sizes. Listed below are the included solids for each file. Additional usage instructions can be found in each scad file.