I didn't like the chrome knobs that came with my Android stereos so I made this one to print in black. I'd recommend printing slowly as there are lots of ridges to match the original's appearance. I printed with the standard 0.4mm nozzle and Polymaker ASA but it should work with PLA. Just be sure it will fit the stalk of your stereo.

The bore measures 5.2mm from flat to edge of the circle.