A Catapult made from Knex

Step 1: What You Need

You will need:

1 Yellow Rod
4 Blue Rods
4 White Rods
1 Green Rod

6 Red Connecters
2 Yellow Connecters
4 Single Grey Connecter/Stopper things

2 Halves of a Broken Yellow rod (optional - I broke one and found it made a good trigger)

1 Elastic Band

Step 2: The Base

Assemble the 2 halves of the base (pic 1)

Join them together with the yellow connecters, but put the elastic band over one of the white rods (as shown in pic 2)

Step 3: The Arm and Axle

Assemble the arm

Step 4: Assembely

Step 5: Optional Trigger

Pull back the catapult arm, and slot half of a yellow rod into the yellow connecter to hold the arm back. Do the same for the other side.

Load up the catapult then pull out the pins to fire.