Ornate Block by Premium Magic.
An ornate block is displayed suspended by two strings running through a hole in the center. The block is placed inside a small cabinet and the door closed, trapping the block inside. One of the strings is tied around the cabinet as well, trapping the block and cabinet again. Two spectators are invited to hold the strings. On command, the magician instantly frees the block and cabinet from the strings - an incredible penetration effect!
Ornate Block by Premium Magic