RE: Aluminium spinner how to cut?
BTW, when you're opening the prop holes in a spinner, take just a little care to help keep the spinner balanced. It's easy.
When you take a cut out of one hole, go to the other hole and cut about the same amount. You gotta do the other one anyway, why not do 'em both (or all 3) at the same time. If you're using a file, when you take 5-6 cuts out of one, go take the same 5-6 out of the other(s).
It takes no brains to work smarter. And no extra time either.