There’s a mouse in my kitchen. The ethical mousetrap I bought in the local hardware store a few weeks ago hasn’t worked. Despite the bait, the mouse won’t go in it, or it has gone in it but managed to avoid triggering the trap door.

Maybe a larger Lego mouse house filled with cheese on a seesaw so that when the mouse hits the cheese the seesaw flips and triggers the trap door that imprisons the poor mouse.… That was the idea. But it wasn’t so easy in practice. I could get a draw to come down and the seesaw was just a long flat 12 point stripper on some car wheels. That was easy. It was connecting them that was tough.

The trouble with a seesaw on car wheels was that it moved about a fair bit. This needed to be a precision device. You couldn’t have things moving about willy-nilly, not unless they were meant to be moving about.

The Professor found a yellow garage door that he put on in place of a trapdoor. But how’s it going to work? I asked, when he had the door open. What would make the door close once the mouse was in there? I would close the door, he said. So you’ll stay up all night and wait for it to go in there and when it does you close the door? Yes, he said.