How I created a desktop trebuchet (also known as a counter weight catapult) from the rear fork of a bicycle.
List of parts:
- One unserviceable bicycle frame (rear fork must be good).
- 4kg of lead (two 2kg diving weights).
- 10mm bolt or threaded rod and nuts.
- 12mm metal pipe (10mm inner diameter).
- 5mm screws and nuts.
- Scrap metal.
- Thick cloth (a pair of old jeans, perhaps).
- Old leather belt.
- Some fishing equipment (they are really practical).
- Wood glue.
You will also need basic wood and metal working tools, like a drill, drill bits, hack saw, file, etc. The bicycle frame is the only mandatory part. You can improvise pretty much all the other parts. My parts don't actually match the list exactly, because I used all kinds of leftover stuff I already had.
Keep in mind that a trebuchet with 4kg weight is really not a toy for small children. The sling release pin is practically a metal blade that reaches a very high velocity. It will tear skin badly. When firing, keep in mind that the ammo will probably be thrown to the exact opposite direction than where you aimed. So make sure everyone stands next to the trebuchet (not in front of it, not behind it). USE AT OWN RISK!