Cube in a Tube

An aluminum tube is displayed to the audience. A small jewel encrusted cube is also displayed and dropped down into the bottom of the tube. A solid metal rod is threaded through holes in the tube, also passing through holes in the cube. A spectator is invited to hold the rod on each side. The magician merely taps the tube and immediately the cube penetrates the solid rod and falls to the table! An unbelievable penetration effect! Easy to do.