I took some pictures of a couple of Turbo Cars with metal rings:
The tip uses one bearing. It is difficult to tell without disassembling it, but it looks like it has a design similar to the tips of the old turbo 5 Estrellas, except that the bearing well is deeper what allowed for a normal shape tip.
If you look at this one opened, the central axis does not turn. So it seems that a short axle was attached to the body (glued or press fitted, perhaps during molding), the inside of the bearing press fitted to that axle, and the tip hugs the outside of the bearing.
Of those two tops, the tip on the orange one can be rocked just a little with the fingers while on the violet one is pretty firm.
Cometa did a very good job with the metal ring; it matches very well the body curvature. The tops weigh 53 grams.
They are noisy but spin well. I could do 15 gyro flops in a row with 1 second stops between them.
By the way, I also threw my King Cobra (fixed tip, 43 grams). It climbs the elevator superbly!
