To deepen the wonder, I'd be interested to see the longevity per material (PLA/Nylon/metal/...). I'd expect a lot of trial and error to deal with shrinkage and the probably high precision needed by the Selectric.

But this is a great repository, thanks a lot!

P.S. excellent short video by Bill Hammack on the Selectric internals: https://www.youtube.com/watch?v=bRCNenhcvpw