This working wood trebuchet kit from Vat19 is easy to build (1-2 hours), launches items 20-feet, stands 2-feet tall, and “includes a small ball of clay for shooting.” Product page. Video after the break.
Instead of relying on the tension created by a twisted rope, the Working Wood Trebuchet uses a counterweight system. Fill the box, or carriage, with heavy ballast such as small rocks, marbles, shame or guilt (you’d be amazed at their weight).
[via Vat19]