Some of my fondest early foreign traveling memories were going to places in Europe and traveling from city to city where the train and airport arrivals/departures boards used these amazing electro-mechanical split-flap display boards. The last place I saw one still in use was at Frankfurt airport in Germany a year or so before covid (and I believe it’s still there):

Scottbez1 walks us through how they work with a demonstration of his single-digit Arduino-controlled display.

Even better, all the parts, software, 3D print resources, and information you need to make your own can be found on his github page: https://github.com/scottbez1/splitflap

But be forewarned, his estimates run around $200 to make only 4 of these wonderful digits.

Also, there are now companies around that will make these displays for you:

• https://www.oatfoundry.com/split-flap
• https://www.vestaboard.com/

But be ready to pay $2800 for even a basic model. This guy does a decent job summarizing the current offerings.