The Wooden Wrist Chopper is always an entertaining routine for older children or adults. 

You get a spectator on stage to help you. Then ask which hand he writes with while pulling prop up from the suitcase... You open the frame and show that it contains a blank metal blade. You can potentially demonstrate how it can chop cucumbers before you lift the blade again and ask the spectator to put his hand (the one he writes with) through the hole. 

This is a golden moment. Everyone holds the breath and there is an opportunity to get a few good laughs before resolutely pushing the metal blade down through the spectator's hand. The blade goes all the way through the hand, but the spectator can pull out his hand - fortunately still intact. You can warn the spectator to be careful not to clap too much, before thanking the person for his courageous efforts.

You receive a hand guillotine made of dark wood.