Step 1: Materials
1 baseboard (1" thick, 6" x 9")
1 lever arm (0.5" thick, 1.5" x 12")
2 side supports (1" thick, 2" x 8")
2 sturdy L-braces and appropriate screws
1 hinge (same width as lever arm) and appropriate screws
1 small eye-screw (extra one in pic)
handful of rubber bands (find some with varying elasticities to allow for adjustments in catapult strength)
(ignore the spring in the picture, turns out I didn't need it)
Power drill (or screwdriver if you're feeling adventurous)
Staple gun (and staples, obviously)
Sandpaper (if you have options, use rough sandpaper to give you the shape you want quickly, and then fine sandpaper to make it really smooth. if you don't really have many options, I would place a strong preference on fine sandpaper)
Step 2: Attach Side Supports
For me, the L-braces alone were enough to secure the side braces down, but if you have smaller L-braces and they don't quite do the job you can improvise with screwing the side supports into the baseboard (just be careful not to split any of the wood)
Step 3: Attach Lever Arm
Step 4: Restrict the Lever Arm's Movement
Screw the eye-ring screw into the lever arm a couple inches up from the hinge. Push the rubber band through the hole in the screw and loop it through itself to secure it to the eye screw.
Here's the tricky part:
Depending on the elasticity of the rubber band you use, you'll need to place this next screw somewhere along the center line of the baseboard so that the rubber band stops the lever arm from falling flat on the table when you fire something from the catapult. I recommend using a screw with a very wide head and leaving enough space between the top of the screw and the baseboard so that you can loop the rubber band around it and it won't come undone accidentally. (See photos if the wording of that doesn't really make sense)
Step 5: Quality Control and Testing
- The catapult doesn't fall apart
- The lever arm swings easily
- The rubber band safety catch successfully stops the lever arm from falling flat on its face, but also doesn't restrict its forward movement too much (readjust the screws holding the rubber band if it doesn't work)
- It doesn't kill people (if it does, consult a lawyer and then adjust the catapult to not kill any more people)
If your catapult works successfully, you'll probably notice that it's destroying your rubber bands little by little with every practice launch. Guess what we do in the next step?
Step 6: Sand the Lever Arm
Step 7: Secure the Rubber Band
Step 8: Drill an Ammo Cavity (Optional)
ALTERNATIVELY: You can glue a plastic bottle cap to the top of the lever arm to give you a nice little ammo slot without sacrificing potential wood strength.
Step 9: World Domination
If world domination isn't your thing, on the other hand, it's great for flinging coins and small objects at those inattentive enough to walk in front of your mighty catapult.