Both the Bill and Disk Freely Examinable
You ask for the loan of any denomination bill and show a small metal disk.
Explain that the disc is made of an unidentifiable material that you found while visiting what was rumored to be the site of a UFO crash!
Begin to rub the disc across the bill, suddenly it appears to melt halfway into the bill! Then cause the disk to actually POP right through the bill and into the spectator's waiting hands!
Fully Illustrated instructions!
No complex moves or involved handling!