8 foot cube, looks like 1 ping pong ball sized LED (from RayWu) every foot. Uses Teensy with ESP32 for wifi control. I suspect a PB would work just fine for this. 8x8x8 is 512 pixels. Trivial to map, add a sensor board, and all that is left is to code up fun 3D sound patterns.
If you built this with output expanders, you could even make it so you could go inside the cube (each strand hanging down… Using @wizard 's method of doing a collapsible cube). Add a expanding mount (a portable 10x10 popup shelter?) And you could take it places.