The plastic knobs on my 924:s heater panel began to disintegrate. New ones are unobtainum or very expensive.
Made this variant after a long trial and error process. This one is possible to put on and to get off the levers with only a little persuasion. :)
The knob is a bit difficult to print, I printed mine with the knob part down, but that way i have to file and flame polish the knob before use.
Oh yeah, two of the original knobs have an arrow on the side... you can hardly see them so i omitted them.