There are a few folks here with 3D printers and I seem to remember LeftAngle did an instrument binnacle at one point. And if you're reading this LeftAngle, you're partly responsible along with a guy at our archery club, for me spending far too much time designing stuff for my 3D printer !
I'd imagine the best place would be in the Technical section of the forum with a stickie topic ? First post states that only links to STL files are posted and in that way the topic won't get cluttered up with comments and making it hard to find things. Pistonheads (car forum) does something similar with public domain software, apps, etc. where it looks like you just add the link to the first post.
The downside to storing on this website might be file size. Personally I think it would be better to have a stickie topic with links to Thingiverse for the actual STL files ? That way they are available to all and not just forum members although of course there's nothing to stop a link back to the forum from the STL file descriptions.
But yep, I'd go for it.