It works in exactly the same way as my DIY stackmat display. You can find the documentation for that here: https://jayanth-rajakumar.github.io/ledmat
The schematic for this is here: https://jayanth-rajakumar.github.io/btmat
Depending on what you already have, this should cost around $15-20 to make.
I wrote up a long article describing how to put everything together, and it includes a 16-minute video tutorial. It also contains some interesting technical background. Check it out here...
