Got my shit together enough to test my siraya tenacious resin out. It's very UV-sensitive so it hardens quickly, but it still has a bit of flexibility and tackiness so it works okay for making stamps in a 3D printer. Maybe setting up a stamping rig and conventional stamping resins would still be worth looking into...
cc @deadrose
And the less said about that disaster of a kirby stamp back then, probably the better.
@deadrose Nooooo D:
@elfi I think I still have it!