Cray Red Button
I used to work at a site that had a lot of mathematical modellers. One of the Cray Supercomputer models we used was just the right height for a raised elbow. The designers hadn't considered this but did consider the perfect place for an emergency stop button was on the top of the box. We put a plastic cover over ours so no one ever accidentally shut the thing down. Seeing this a Cray engineer tells he'd been to a site that had used half a coconut shell for the cover.