... and while I'm putting up projects that kinda-sorta work, I have this as well. Running on a Pico Pi, bluetooth for IO, and Scott Bezek's Chainlink driver board.

CAD design started with David Kingsman's design and quickly diverged because I wanted it to scale. The core frame holding the letter-units can be tiled both horizontally and vertically.

Still working out mounts for the electronics and a few other issues (good stepper motors are hard to come by in bulk for a hobbyist?) before trying to crank out a huge display.