matrik slotFrame Slot. Check the side of the frame with the slot is facing the rht side of the RGB LED Matrix. Install Acrylic to Frame. The sheet of black LED acrylic is insertedRGB Matrix Slot Machine. by Ruiz Brothers and Jeff Epler. published June 17, 2020, last edited January 21, 2025. posted in LEDs LED Matrices 3D Printing CircuitPython.