DIY Paperclip Trebuchet.

Instructables has this step-by-step guide on how to make your own 3" trebuchet [wiki] from paperclips that can throw little balls of blue-tac to an amazing 4 feet.

You will need:

1 pair of pliers (needle nose would be best but i don't have those at work)
1 pair of scissors (yay for scissors)

7-8 paperclips
sellotape
thin string
blu-tac
a piece of corrugated card (approx 6X6")
Ballast (I used a bunch of batteries from our recycling box)

Link - via digg