I had some made. I tested them polishing the part and they did not do an adequate job.
So in the future I'll have them available unfinished. Like a sand cast finish.
I'm going to see a local polisher but it will add about 50.00 per unit.
Pm me if you want to buy one.
I have made the plastic part and it works fine,
I twisted a tach head case in one 100 times and while it did damage the plastic between the divots they were still intact and functional.
I have some other plastics to test out. And to see if my manufacturer can make them out of a better plastic