Summary

This clamp is simple but effective. Made with a few printed parts, a roller, a steel rod from an old toner cartridge, and a 3.5mm nail. The lower clamp has a 7.5mm hole through which a small piece of 9mm-long silicone rod (the hot type) is inserted. This is because the first design didn't fit tightly enough, and the clamp would slip as the screw was tightened. It's not absolutely necessary, but a guillotine-type part was incorporated to cut the silicone rod to the required length using a utility knife