A simple rubber band gun made with a clothes peg, ruler ( preferably wooden), sticky tape, two thumb tacks and a rubber band.

Step 1: Getting Started

To start insert a thumb tack into the end of your ruler.

Step 2: Next

Tape your peg to your ruler on the side that has the tacks point.

Clip your rubber band in your peg then over the tacks point.
Then open the peg to fire.
If the band sticks to the peg just higher or lower to point.