A fully working proof of concept ratchet mechanism made to fit some of the bolt heads found on thingiverse. It's quite sturdy and works surprisingly well! It would be fun to measure the load it can take, I'm guessing plenty! The springs I made works but I have not put much time into making them perfect. Since I like to show the insides to friends the springs should have had a quick release or something.Download and print the parts. 1 off the Castle (with or without handle) 1 off the Crown and 4 off the Spring A multicolored ratchet is more fun! I used 20% infill and 1.2 mm walls with 0.2 mm layers and it came out plenty strong. Assemble and enjoy. The socket size is 75.5 mm and fits snug around Bbuonomos "Large Threaded Bolt and Nut" at http://www.thingiverse.com/thing:4880 If you scale up the "Wrong Way Nut" from VeryWetPaint to x1.536 it fits as well. It's at http://www.thingiverse.com/thing:12728 If you tell me the print scale needed for other nuts and bolts from thingiverse I can add the specs and links here. Optional: After assembly, heat the protruding spring ends to lock them in place so that they can't rattle loose during heavy use ;) UPDATE: I uploaded a version of the castle with a handle as well, please share a picture if you print it since I haven't yet. I included the Solidworks model files as well. UPDATE 2: I uploaded the correct solidworks files this time. (Thanks Dotten)