As of next week, KiCad 9 should be about to release.
One of the many exciting features, to me, is that it now includes a footprint generator that I contributed, for capacitive scrollwheels.
It’s based on the Atmel (now Microchip) appnote AN294 Self-Capacitance Sensors.
Interestingly, the image displayed in the appnote does not actually conform to the requirements set out in the text. Specifically, the corners are too pointy.
Here is the default wheel in the generator I wrote, with the 1mm corner radius.
Generators are fun, though. I haven’t used the output for mine in a real device yet, but maybe someday I’ll get a selection of them fabricated onto a PCB and test them out. iPod, I’m coming for you.
To use it, go into KiCad’s footprint editor, and press the button to create a new footprint from a footprint generator. Select your options (inner and outer diameters are the critical ones), generate the footprint, and then save it into your library.