Smart Guillotine by Tenyo Magic

The magician invites a spectator to insert her finger into a hole that passes through a transparent frame. He then slides a solid blade into the top slot... and lowers the blade. Magically, the blade penetrates completely through the spectator's finger! It looks exactly as if the finger has been sliced through, but when the magician lifts the blade up, the spectator's finger is completely unharmed.