Based on the design of MAKERFAM, I made some important modifications, lots of users requested.
All parts are now separated in single files, so you can print any part as you want in case of failure.
Additionally I added some extensions which makes it possible to assemble the rubberband-gun without any glue. Just stick them together and fix them with two more bolts. That's it. For users, which like to make more modifications, I added the original file for FreeCAD.