This model is for anyone who wants to build a custom bass knob for their audio project, meant to be printed in a translucent filament/resin for the LEDs to light up. I did the knob itself the same way so it would capture the ambient light from the LEDs in the box itself. They do make LED potentiometers that you can get and add, which would have the entire piece lit up. I made the hole in the bottom big enough to fit a 1/2" (12mm) cable gland inside (NPT fittings specifically). The volt meter slot if for the small 1" by 0.25" volt meters. The power/rocker switch hole on the side is for 3/4" round switches. Uses standard 6mm by 15mm shaft potentiometers.