The four pieces (beams) featured in the middle of the two side pieces are placed at the botttom. The three short beams are secured / glued. The beam with the catapult arm is free to rotatewithin the round slots.

The beam featured on the right is securedat the top of the two sides, with an extra at the top of the two sides, with an extra small piece in the middle of it which actsas a stopper for the the catapult arm.

An elastic band goes around the middle ofthe catapult arm, above the top middle beamand is wrapped and secured around the bottom back beam.

The stopper needs to be placed with the shorter side at the bottom so that the catapult arm rests flat against it when in the upward position.

HOW TO CONSTRUCT YOUR CATAPULT