by danielpublic, published
Design, parts, files: GPLv3.
Pics & doc: CC-BY-SA.
Made with FreeCAD:
reprap.org/wiki/Freecad (Resources etc.)
Inspired by Kean's M3 Thumbscrews.
With added room for a penspring.
Play around in FreeCAD; adjust & print. If you still need any other sizes than M3, feel Free to post the specs on the size you want and I'll upload it.