I thought the same thing about the Aluminum Nova Cups Being bulletproof. The rear cup is useless after 1 pack and I just took the CD cup out to refill with a lighter fluid and give it a thorough inspection and it actually is starting to wear pin slots in the side of the cup as well...(at least a dozen runs or so) I can try to get a picture but Its not that cool

Well there goes $40.
I will just go back to the Losi XXL HD plastic cup. I looked at the one I was using for over a year in the rear diff and it looks new...

the ring and pinion also look brand new.

I guess those little metal inserts in the XXL really save the cup. I think a CNC cup designed after the XXL cup would be bulletproof, but not cheap to get CNC'd...