A problem I discovered while researching this is that it is hard to create a large matrix in a way that does not use an exorbitant amount of power, especially if you want them to be individually addressable. That said, there are several tutorials online (such as this one: http://www.instructables.com/id/Make-a-24X6-LED-matrix/) that teach how to create 2D LED matrices that can be connected in series and run off of individual microcontroller pins. These cut both the amount of pins in use on one controller down as well as the amount of controllers you need overall. People have also made 3D versions of this kind of matrix display, to create animations such as this one: https://www.youtube.com/watch?v=SyuLhEUImng
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