Today, as a museum gallery host, I watched a design failure - I'm confident it was unintentional - unnecessarily block access to one of the exhibits. I think it was because of a certain way the design team was all alike.
It was a mock 1920's telegraph, attempting to highlight communications from a small town that did not yet have telephone service. It has a vigorously ruggedized mock telegraph key for the guests to try using morse code to spell out messages. When pressed firmly, it sounds a buzzer so the guest can hear the dit-dah patterns of morse code. It has the same functionality as Morse code trainers had in the era of morse-using telegraphs. The one at the link has a key, a copy of the Morse code version in use at that facility, a buzzer, and a light.