ITP students Will Jennings and Lia Martinez built a small catapult (not a trebuchet in the strictest sense) that, when pulled back and released, announces “Banana” and triggers a video projection of said fruit flying into the wall. From Lia’s site:
The technical part wasn’t too difficult. Will wired up the catapult with a reed sensor and an Arduino (we had a back-up tilt switch in case the glass of the reed sensor shattered, but we never had that problem). The Processing code is simple as well, where there are two states and two behaviors depending on the state: catapult up will play this, and catapult down will play this. We used wav files for the audio and a CSV to mark entry points for the video.