My students and I designed this bracket to slide onto a 3" tack strip that goes around my classroom. We designed it to mate with a NEMA-17 motor mount (http://www.thingiverse.com/thing:18019) for use in a Polargraph printer project. I'll also be uploading a "blank" that you can use as a jumping off point for your own projects if you have such a strip.
Print and enjoy! At least on my printer it didn't need any type of post-processing.