Well, this is my Knex catapult. It's pretty small, but also extremely simple. Great for bombarding toy soldiers, sand castles, ect. (I did not see this design anywhere, so if it looks simiar to someone's, sorry.)
Step 1: Pieces
The pieces you'll need are:
1 Snowflake (White)
4 Purple "3d pieces"
4 Blue "3d pieces"
4 Light Blue rings
2 Grey rings
2 Tan Prong clippy things (see pic.)
2-4 Rubber bands
Step 2: Make the Base P.1
Connect to yellow rods to the 0 and 180 degree spots (Both ends) of a yellow connector. Repeat, and attatch the two with a blue rod.
Step 3: The Rest of the Base
Now, get all the Blue and Purple 3d connectors. Attach a Blue to a Purple, so it has a flat base, repeat for the rest of them. Then, attach onto the ends of the Base, so the Purples line up with the Yellows. (See Pic.) Attach a side with one of the remaining Blues, so the Blue rods are parallel.
Step 4: The Base of the Arm
This is the part that you will evantualy attach the arm to. Put, in this order, a Blue Ring, a Blue Ring, a Grey Ring, a Grey Connector, a Grey Ring, a Blue Ring, and a Blue Ring. Attach this to the other end.
Step 5: Going Up
Attach the four Red Rods (say That ten times fast!) to the four corners, then attach each pair together with a Red Connector.
Step 6: With an Insane Amountof Unimagination, Step 6
Attach the two Tan things back to back in approximately the middle of the remaining Yellow Rod. Then stick this contraption through the two holes in the two Red Connectors.
Step 7: The Arm
The Sling-ey part.
take the Snowflake and attach all seven White Rods. Attach this to the Gray Rod. You noow have an Arm. Attach the Arm to the Gray Connector.
Step 8: Finally, the Final Step!
Almost Done! Now attach rubber bands to the back of the Arm (The Hand?) and the Tan Prongs. Then attach a rubber band to the Red Connectors to keep them in place. You're done! Pull down on the "Hand" and let go to fire! Bombard your Army Men's Forts! Lay seige to a Castle! Scare the living out of your cat! Have Fun!