Design: L Pierson, DVM

Lisa has devised a folding PVC trap, and (oh, by the way) has devoloped a remote control box trap!She is not interested in building drop traps commercially, but will consult on design issues.
If you're interested in buying the remote control box trap, it might be available, for a price (around $250, most likely).
Consider using "The Trick", described here to train the cat to go into a box trap, and if necessary, to control the trap door using a propstick and string.