I thought about putting in a Nerf rocket-launching toy, and aiming it where I figured Art would be standing. The launch stand connects to a tube, which leads to a heavy rubber cushion. Stomping on the cushion forces air through the tube and launches the foam rocket. I could have run the tube under the cube wall to the east and disguised it, pulling it out and stomping on it right after the northwest top was removed. This seemed complicated, error prone, and I didn't feel like going toy shopping, so I skipped it.
Art has a catepillar toy that, when stretched, plays music.
I meant to stretch it to full length across his keyboard, binding it with twine, so that he would be forced to endure the music before he could use the keyboard again. This one I just plain forgot to do. Art's arrival could have been better managed. I wasn't really sure when he was going to be arriving, though I had talked to his manager on the previous Friday to be sure that he wasn't going to be out of town. I thought about weaving a spider web of twine in the corners of the cube to impede progress, or perhaps a vertical one dividing the cube in half.