Step 4: install the ammo bucket and rubber band
the ammo bucket is a tiny plastic cup that sugar free drink mixes are packaged in. (like crystal light).
i used one of the screws to poke 2 holes into the bottom of the bucket about 1/2 inch apart.
then i threaded a zip tie through those holes and around the end of the catapult arm and tightened it.
next, i spread apart the tower dowels and slid on a rubber band onto the pipe. the other side of the rubber band goes around the catapult arm and is tightened in place using a zip tie. the closer this is attached to the ammo bucket, the more tension applied to the rubber band - which causes the ammo to fly farther. if you want to experiment with different tension, then double wrap the zip tie through the rubber band and around the arm but do not tighten it fully. this provides enough snug friction to keep it in place whend using it, while at the same time allows you to adjust the tension up or down by sliding the zip tie along the arm.
you might think that because of the acute angle of the arm to the ground that the ammo will fly high and land short, but this is not the case. a ping pong ball flies well over 6 feet and can knock down a small lincoln log house, a cotton ball flies about 3 feet, and a paper wad flies about 4 feet.
This is my first instructable... enjoy!