I needed to firmly hold my bronzefill Maker coin ( http://www.thingiverse.com/thing:1862575 ) in order to polish it but without crushing any of the details. I did not see any of this style vice on Thingiverse so I made one.
Print one of each STL file. The inclined part of the wedges should be sanded a bit to remove the "steps" so they slide smoothly against each other to close the vice.
The vice is much more secure than it looks and will hold any small object up to about 38mm x 38mm but can be scaled up for larger objects (within reason). The inserts hold most small things, but you can easily customize them to gently hold specific shapes. It fits together into a compact "puck" when not in use.
Printed at .3mm, three perimeters, three top/bottom layers and 50% infill is more than strong enough. I used eSun ABS but I'm going to try some of their PLA+ since it's supposed to be tougher (and we're neighbors so they give me samples for free;-)