Picture of Quick and Easy Wooden Catapult
This catapult is doable in about half an hour to forty-five minutes. It doesn't launch very far due to the elasticity of this bungee cord, but a motorcycle strap would much work better.  

Submitted by Powell Middle School for the Instructables Sponsorship Program.

Step 1: Parts

Picture of Parts
3" hinge (I bought a door hinge from Walmart with the screws)
8' of 2x4
12 decking screws
4 eye bolts
3' 1/4 inch rope
90 degree angle support
Tuna Can or other small 3" diameter can

phillips screw driver bit
3/8 inch drill hole bit
How far does it launch? I want to use it in my yard for my dogs
SCGober2 years ago
I did this as a kid and used a bike tube. The tube would really fling it. Can also take a frozen juice can and cut it in half to use as a cup on the end of the arm. Works good for throwing fruit or rocks or whatever.
I may try this but using a triangle base for stability.and some bike tube. Please put that Bungy thing in the bin. They are dangerous, People have lost eyes and one killed a trolley boy in Oz.
Mistwalker2 years ago
Nice, simple design. I might add a pulley to the top so the bungee cord doesn't wear as quickly, and maybe a block so the arm will stop at the optimal angle to get the best distance. Also, if you have a quick release mechanism of some sort, instead of a rope that has to be pulled along through a ring behind the arm, that might improve the speed, as well.

Good job, though. You've got me wanting to build some sort of siege weapon, now.
antioch2 years ago
Nice one because it's so easy and simple

by the way filesizes for the movies seem incorrect (for 2013-05-20 19.25.52.mov it says (516x290) 22 KB but it really is 20.7mb in size)
antioch antioch2 years ago
I just started to wonder if the ball is losing quite some momentum due to the tuna can's design.
As the catapult's arm accelerates the ball will in addition accelerate from one end of the tuna can to the other (upper) and then bounce against it. possibly at a very bad time which will work against the momentum gained through the catapult's motion.
or, more likey, it will give the ball a detrimental (slice) spin. (which is what seems to happen in your video)
My local tennis ball fiend says "Two Paws Up!"
Great work