This trebuchet launches softball size water balloons 50 - 70 yards using human (kid) power. It is portable (quickly folds down for car top carrying) and uses easy to acquire supplies found at Home Depot or Lowes Home Improvement.
I originally designed this for the kids area of the Lake Eden Arts Festival (theLEAF.org) where we launched water balloons at a large cardboard castle.The video below shows the trebuchets in action at TEDx Katuah 2011 where I was asked to provide a "hands on science" experience for conference attendees. At the TEDx event we launched "deer apples" (rotting apples) instead of water balloons and our best throw with the apples was 85 yards.
The TEDx Katuah event was held at the Pisgah Astronomical Research Institute (www.PARI.edu) which was originally designe for the NASA space program. After NASA, the CIA used PARI to spy on the Russians. One of the employees at PARI is Thurburn Barker (pictured here with my son). Mr. Barker worked for NASA during the early days of the manned space program and he was fascinated with the trebuchets.
Since the TEDx Katuah 2011 event I've continued to improve on the trebuchet design, especially the end of the throwing arm.