This is a catapult built into an altoid can. It uses pretty common items:
1x Altoid can
2x Clothes Pins (ones with springs)
2x Rubber Bands (Preferably small ones)
1x Assorted piece of flat wood.
Hot Glue Gun
Small Metal Saw
First thing you should know is that not everyone of these things turns out perfect, or even useable. If you dont think any of the things I used to make this is perfect, do not be afraid to change it. The one that i made during this instructable turned out to be a flop, because i tried some new methods, compared to the last one. Ill try to include notes to help you make a beautiful catapult.
Step 1: Prepare Fulcrum
Toothpicks, or whatever round piece of wood you used (i used a "bamboo skewer", which turned out to suck) Try to use something as thin as possible
First, Remove the metal spring things from the wood of the pins, and strech them out a little, so the legs are about 1/2 an inch apart when they stand up.
Next, cut a piece of the toothpick that is just a little longer than the width of the can. Now, shave the toothpick down so that it fits smoothly into the hole of the springs. Shave it down with whatever you feel like.. scissors, file, teeth... and make sure to clean up the mess.
Step 2: Throwing Arm Addition
For the throwing arm, cut a piece of the clothes pin's wood that contains the largest (widest) hole [see pictures]. Use a roundfile, or almost anything to make this hole just a little bigger, so that the toothpick can go in, and not be higher than the flat part of the pin.
Now, cut a piece of the long, flat wood. It should span from one end of the can to half way between the cut and the other end. (See pics if needed)
This board should not be anywhere near as wide as the space between where the two springs will be.
Now, hot glue the piece with the hole to the piece of wood where shown in the picture... do not leave the toothpick in there while gluing.
Now slide the toothpick through the hole in the can, and through the first spring, then the arm, then the other spring.
Proceed to glue the legs of the springs into place... DO NOT WORRY ABOUT OVERDO-ING IT WITH THE GLUE. i ended up having to create a sea of glue on the legs near the end, then tend to pull up easily.
Step 3: Start the Trigger
Step 4: Take a Damn Break
Step 5: Final Steps
Also, add a little box, to hold items you are shooting better. (Pic 2)
Cut the end off one of the toothpicks, to make a small trigger.
Now tape/glue (i suggest a heavy amount of glue.. even though it sucks to change the band once it breaks i used tap in the example, and it didnt stick enough) to the bottom of the can. (pic 4) Now turn the throwing arm the right way, and rig up the two parts of the rubber bands.. one by one.
Once they are on, glue a little bit at the end, to prevent the bands from slipping off.
Now, put that little stick (aka. trigger) between the arm and the can. Now load it and pull the trigger back to fire.
This video.. i made it about a year ago.. and had to convert it to swf to show it on mywebsite.. and not take up a ton of space.. but since then, i lost the original avi, because we got a new computer, and now i have to convert it back to mpeg, so sorry about the brandings on the video..