Expansion (DVD and Gimmicks) by Daniel Bryan and Dave Loosley
Expansion has to be seen to be believed -- it really is an absolutely perfect close up effect.
A card is selected and signed (any card, no force required). The magician then punches a hole in the card. Handing the card and a borrowed coin to your spectator, a challenge or puzzle is set. Can they get the coin through the hole without damaging the card?
They can try as much as they like, but it's painfully obvious the coin will not fit through the hole. Well, not unless the spectator can pull a miracle out of the bag!
You now offer to demonstrate how to solve this impossible-looking puzzle. You visually stretch the hole until it is big enough for the coin to fall through comfortably and then, with just a flick, the hole visually shrinks back down to its normal size.
At this point, the card and coin are handed back to your spectator.
Expansion is easy to do, comes with hand-engineered gimmick and full instructional DVD explaining Dave Loosley's commercial handing (simply supply your own regular hole punch and matching deck and you're set to go).