
That shouldn't be too pricey, and probably possible to DIY if you can lay your hands on some old parts and you're handy with Arduinos and the like.
I think I'd prefer the ones that flip horizontally for a clock, though.
( , Sat 2 Nov 2019, 0:01, Reply)

For about £3 imported from China, but they only drop one flap at a time, so they’re not quite as fun...
( , Sat 2 Nov 2019, 6:34, Reply)