Dave,
This thread is all screwd up on my computer. I can't see any of my own posts after I post them.
Vince Giampa had an alluminum throttle knob made for his plane the diameter looks the same, but he had it made longer/wider. It looks like something you would see in a larger airplane - very cool. Maybe you could have your machinist add a little material to make them more like Vince's.
Vince do you have pictures?
Carl & Robin Lee
1144J
PRB
Starting a new thread. Hopefully faster.