A Physical Portal Illusion Catches an Object on One Side and Fires a Matching One from the Other

James' Programming built a physical illusion inspired by Portal: throw an object into one frame and a matching object appears to shoot out of the other. There is no video compositing; the entrance detects the incoming object while a flywheel launcher at the exit fires a duplicate.

Time-of-flight sensors detect the approaching object early enough to compensate for the launcher's mechanical delay. The build took about nine months, and the full detection and automatic realignment sequence was still finicky, succeeding roughly one time in twenty.