Cause i can not find precise led ring.
There's no existing solution to get 16 pots in line with its rings which fits in a 19“ rack face.
So i tried to design it.

The goal:

• 20mm diameter ring.
• 32 matriced bicolor Leds on SR with PWM support.
• Width<27mm between 2 rings for 16 pots or encoders to fit in a 19” rack.
• Support encoders and potentiometers 270° and 300°.
• Low profile for integration facility.
• No component on top side except leds.

How:
I need to drive 32 leds, 4*8. The trick was to find a register which has 12 ouputs and compatble with SR line(DOUT). The NXP HEF4894B was made for it, i's a 12-stage shift-and-store register, its operation is very similar to that of the 74HC595(serial I/O, serial clock, parallel load) except that it has a strobe input for PWM function.

Autocad design rendering:

In fab at Osh Park …