We made a BLACK LIVES MATTER light up protest sign for night time use that works and looks great using a 64x32 RGB LED Matrix, Adafruit Feather, and CircuitPython.

These panels are normally used to make video walls, here in New York we see them on the sides of busses and bus stops, to display animations or short video clips. You can make them portable and informative.

The matrix can also display the names of Black people killed by the police which the Washington Post compiled in to a database which is a datasource on GitHub. See: saytheirnames.glitch.me