Man I love those things. I have warm memories of standing in Italian train stations as a kid and letting the clacking wash over me when they did a full board refresh. It’d fade out like a rain stick as the stragglers that started furthest from their target letter trickled in.
Now it’s all LED, which is way more practical and so much less magical.
Reminds me of the “flip flap” boards in old train stations. Like https://www.vestaboard.com/