Summary

Rockler makes these amazing tools for the workshop but unfortunately I can't buy them locally.
So I made them myself. The middle part can be printed in PLA with a high infill to give them some strength and weight. In the centre there is space for a threaded insert. The top and bottom I made from a liquid rubber using the rubber mold part.. Once it's dry just glue them to the middle part.
Printing it with with flexible filament (antislip) might also work or just find some none slippery material and cut to size.