My RV4 has the standard vans throttle quadrant, with round knobs for the throttle and mixture. I would like to replace the mixture knob with one that has the ridges, like in the image below. I googled and googled and can't find where to buy a knob like that. Any ideas? I already tried carving some texture into the round knob, but it is a really weird material, and its not turning out well.
