I built an LED matrix board for a future project. I designed it so multiple boards can be strung together to form a larger display. I also used SMT for the design. There are no mounting options save for hot melt adhesive. It uses the popular MAX7219 driver chip and one resistor.
If you do a Google search for useless machine you will see a bunch of these. I saw several people’s useless machines and I wanted one so, I made one. I used a small servo, 3 AA Batteries, and a simple 555 circuit to control the servo. It was a quick and dirty build but it works.