Ha,ha,ha, While I've yet to see a Styrofoam hammer. I have seen high density urethane foam hammers, Balsa-wood chisels might be interesting.
In most cases plastics do not fare well in a metal fab shop, but a plastic vice might have a purpose in an environment where other non metalic materials might be used as the preferred medium IE model cars model airplanes working on cell phones printed circuit boards ETC. None of which are of much interest to me though.
I place a PVC vice in the same category with a table saw, a drill press a belt grinder and other machines made out of wood or plastic. Some people make them and use them with good results. Heck I have even seen a metal lathe made out of wood in a museum that was over 300 years old so why not a plastic vice? LOL