Fine work. I'm lucky if I can check my Z's tire pressure without banging my knuckles. I want my knob similar to your first one, but with a 1/4 inch taper ( larger at the top with a slight dome) and about 1/2 inch shorter. The diameter looks fine. Mine can be hollow so it extends below the threads. I would also like my initials (LBC) engraved in the top with the letters filled in with TR paint. How much are they? Delivery? Is Delrin heavy? Would a heavy knob help to eliminate the rattling you hear about on this site?