Im trying to make a controlable 310x488mm led screen made up of many 8x8 led matrices. The controller for this project willbe a rasberry pi. I need to be able to put simple geometric shapes on the screen since it will be used to teach kids with down syndrome. It will also have a touch panel on top of screen for interactive learning but for now i need to know what is the best way to go about the circuit design. I was considering using a whole lot of demultiplexers ,arranging them on x and y to select the desired led that will turn on. The rasberry pi doesnt have enough pins to control all the multiplexers .So will i have to use another set demuxes to control the demuxes controlling the leds? Or is there a simpler way?