That was hard! I did "shower of masks" and it took me half an hour (for 30 pieces). Even when you get them in place, the lighting isn't much different so sometimes you can't tell where you still have to go. I had a piece "left over" and it turned out I had a piece in the wrong place and didn't even know it; only accidentally went over it and had it move (pieces in the correct place won't move). LOL.