matrix slotRGB 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.1 Spindle: Internal screwlike pin that fits into the diagonal slot to hold the ends of the matrix band. When the retainer is assembled, the spindle point must be clear of the slot while