Mixture control knob with ridges, where to get one?

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.

DJM Mfg Inc products

Hi CATpart

send me a e-mail and I can hook you up

Dayton

[email protected]

Thanks Dayton, I sent you an email.

FYI the weird material turned out to be wood, lol. I got confused, after using a file I rinsed it off and the wood swelled.

Thanks again Dayton (and thanks Rosie for alerting Dayton to my most urgent need)!