In this video, we learn how to make a pen gun. You will need a rubber band and a pen with a cap. First, disassemble the pen and leave only the ink tube and outer shell of the pen. Next, put the rubber band on the side of the outer shell of the pen and tape it down firmly. Finally, you will place the ink tube back into the outer shell and when you pull on the rubber band and release, it will shoot the ink tube out. This is a dangerous tool so be careful where you point it and what you're shooting at!