Knobs 1-3 are from some of the folks on the PiDP-11 forum.

I made a few changes, which are in knob4.scad. That is the one I printed. I tried it two ways, one printed in black, and sprayed with flat black paint. The white line was done with nail polish very carefully.

I also tried printing in white, and brushing on Floquil engine black. The white is not very vibrant on that one, so I used the ones with the nail polish on the PiDP-11.

This is an open-source project. This work is licensed under CC BY-SA 4.0:

https://creativecommons.org/licenses/by/4.0/

Here is what the knobs look like on a PiDP-11: