Our project is infact an Arduino with Serially Interfaced MAX7219 Operates an 8X8 LED Matrix to display a heart pattern. The MAX7219 IC is a serial input/output common-cathode display driver that ...

In this case, the recipe simply calls for three MAX7219 dot matrix LED modules and a Raspberry Pi Pico, although you could swap that out for your favorite microcontroller if you wish.

However, his latest video uses some a MAX7219 to create a 600 character scrolling LED sign. You can see a video of the thing, below. Spoiler alert: not all characters are visible at once.