This is the mini version of the stage trick arm chopper.
Effect: Performer shows a wooden frame with holes, and a chopper blade, that cuts through beans, or a cigarette placed in the holes. Then he places his finger in the hole in the middle of the frame, and passes the metal blade right through the finger, obviously with the finer unharmed.
Easy to learn
Looks like the blade really passes thru your finger. It can cut the other objects at the same time with out cutting your thumb.
Note: Blade is not sharp enough to cut your thumb. Once you know the secret your thumb will be just fine.