>Also, any tips on precisely cutting the velvet holes for the LEDs?
I didn't cut holes for the LED heads, I just poked the LED wires through the velvet after the velvet was already glued onto the PCB. So the LEDs sit on top of the velvet, which sits on top of the PCB. I borrowed a large sewing needle from my wife to poke the holes for the LED wires through the velvet.