The best way I've found for letting resin set when making pins, magnets, or plaques, etc. is to use a spool of thread (two spools set apart from each other if the piece is big), square dice, small square blocks of wood, or cut up pieces of 1" diameter dowels to rest the shellacked pieces on. Make sure the piece's diameter is bigger than the spool surface. This way, the resin can drip or run without the hassle of sticking to the setting surface.

If your pieces are small and can't be held from the underside when painting the resin on your piece, you might want to put easy to remove double stick tape on the spool or dowel (don't use the really "sticky" permanent type tapes, or you'll have a heck of a time taking the piece off the spool), then paint on the resin using the spool as a handle.

When the resin is set, you can just pop it off the spool with no problem.