Guns
The more you are able to pull on a rubber band, the more energy it stores, and the more energy it stores, the farther and faster it will go. The concept behind a rubber band gun is to allow the rubber band to gather as much energy as possible and fire off to great lengths. There are many ways to make a rubber band gun, but two stand out as easier than the rest. One kind fires the rubber band, and the other can fire paper clips. But never aim at a person or animal when firing objects from a rubber band weapon, as rubber band weapons are difficult to control and can inflict real pain.
Take a regular pen and securely tape a strong rubber band to the flat end of the pen. Roll up a small paper ball, nest it in the bend of the rubber band, pull back, and let it go. Now you've made a very simple rubber band gun.
The other kind of rubber band gun involves shooting the rubber band itself. You will need two pieces of wood, one about 18 inches long and the other about four inches long. Form them into a T-shape with the four-inch piece intersecting the eighteen inch piece about three inches down the longer piece. Attach them using glue, screws, or nails and you have a rubber band gun. Stretch the rubber band along the long piece and use the shorter piece as a handle. Roll the rubber band off the long piece until it fires away. Once you have fired the gun you may want to make a small shallow notch in the back where you secure the rubber band so it stays in place better.
Bow and Arrow
Take a standard pen and remove the ink cartridge. Cut a hole at the top and bottom of the pen casing and then thread a rubber band through each hole. Tie the rubber band in a knot at each end to secure it in place. Now take the ink cartridge, load it into the rubber band as an arrow, and fire away. These are fun little projects you can use to occupy some time, but never point these at people.