When working with small models sometimes my fingers just are too big. So I made a fully printable hand vise.

Print everything in PLA with a layer height of 0.2mm or lower. Support is not needed. The thread is close to M12 and should work directly after printing. Lubricating the thread is recommended - I am using candle wax for that. If you want, you can re-cut the thread with an M12 tapper, but that should not be necessary.
For the hinges I designed hinge rivets. To install the claws insert the claws and the hinge rivets, heat up a screwdriver and press it on the small end of the rivet. The rivet will melt in place.