Scott, I tried to apply some highlights after applying a patina this way, and was surprised how difficult it was to remove ANY of the patina with a scotchbrite pad.
Scott, pour some ammonia in a container with a lid, suspend the copper piece above the ammonia (not touching) and allow the fumes to work on it overnight. You get a very even, amazingly tough blue-green patina.
I liked it, except for the plate tossing and singing scene which I found dumb. Reminded me of Disney's trend of making scenes where everyone is singing and dancing.