Trebuchet uses silk work cocoons, from silk worms I hand raised my self. It was an interesting experience raising my own materials for my work, and probably on of my earliest pieces in which I consider the idea of self sufficiency.
The counterweight system is made of boulders and bricks, found in the The River Thames, with a steel cage welded around them.
I like the contrast the delicate silk cocoons make to the heavy steel counter weight system that suspends them.