A YouTube video of "The Most Useless Machine EVER!" is proving popular among those who'd like to have a robotic box whose only purpose is to turn itself off:
This entertaining device is a version of the "Ultimate Machine" built by US electronic engineer Claude Shannon, based on an idea by Marvin Minsky, the co-founder of Massachusetts Institute of Technology's AI laboratory.
If you fancy putting an Ultimate Machine on your desk to amuse visitors, as did Shannon, there are construction details right here. ®