The technical term is “split-flap display.” But nobody knows the signs by that name. They’re the “neat, flippy signs” or “those old alarm clock displays” or “the signs they used to have at train stations.” They’re signs that update not with lights or pixels, but with a stack of tiny printed tags that flip into place.
Now, these old-school split-flap displays are available for your own home–if you’ve got $1850 left in your domicile’s cute sign budget. This is the Vestaboard, a 37″x21″ mechanical display for your wall. It has 161 spots for characters (also called bits), each of which can display all letters and numbers, symbols, and even a few “art” spots that are yet to be determined–though emoji seem like they’d be an excellent fit.
The magic is that inside each of these bits is a motor that spins like a Rolodex, or perhaps a mini day calendar, flipping the right characters into place. In the modern era, in which LCDs, LEDs, and other blinky lights are so cheap to produce, this sort of solution is absolutely over-engineered, and that’s why it’s both so fun and so expensive.