I bought this trick from my local magic shop a long time ago and I really loved it. You wrap a piece
of rubber around a glass and tie it off with a rubber band. A quarter, or other coin (completely
ungimmicked) is placed on top of the rubber sheet and is clearly seen sitting ON TOP. You simply rub
the top of the coin and it instantly penetrates through the rubber sheet into the glass. If you
want, the spectator can even push the coin through, but like all "gimmicks" just be careful. I use
gimmick in quotations because it isn't really a gimmick at all. Actually everything can be examined.
After a while, the rubber sheets will break though, so you might want to buy some extras.
