Strawbee Ballista
Strawbees are plastic pieces that can be used to connect standard size drinking straws. At a local Hack Space we tried to build a catapult with these connectors, straws, rubber bands and other miscellaneous items.
My design is a ballista (closer to a crossbow in design than a catapult)
Main Beam
The main structure consists of 5 equal length straws joined at both ends with a 5 joint. This provides significant compressive strength.
Side Support
Two straws are inserted at one end and spread to form a triangle. At the front they are connected by another straw.
Legs
The legs at the front serve mainly to raise the front of the ballista to the correct height. They do not provide structural support.
Rubber Band
One or more rubber bands can be hooked into the main beam. Firing is done like a slingshot: The projectile is lodged at one end, pulled back and released. A golf sized airflow ball was launched approximately 10m on the first shot.