I completed my trebuchet. Video here: Trebuchet
Built from this kit, it is a model of the Stirling Warwolf. As they say:
During a siege of Stirling Castle in 1304, Edward Longshanks (Edward the first, King of England) ordered his engineers to make a giant trebuchet for the English army, named “Warwolf”.
With one blow, Warwolf leveled a section of wall, successfully concluding the siege of Stirling Castle. The Stirling Warwolf is generally thought of as the most powerful and most famous of the trebuchets in history.
Now that the model works, the next step is obviously to build a full scale version!