Resin parts (a tip an a question... what a combo!)

Hey guys! I just thought i'd share something i found today when mixing two-part resin. When you put it in the cup to mix, take a drill (i would say dremel but that's too fast) and a toothpick. put the toothpick in the chuck and then near the tip, bend the toothpick so it'll make some waves. Then have at the resin mix. Should be nice and mixed with no airbubbles in about a minute.
Now comes my question... What is the best way to clean up the two-part RTV rubber mold materials? i know once mixed you can just peel it out, but what about individual cups? the blue part never really sets, and i'm FAR to poor to use disposable cups. Any solvents that work? thanks for your time!