I tried the rubber and V-blocks....didn't work out that well. Tried aluminum tape, tried 3M double sided tape. Still not so great. Problem with the V-blocks is that they only contact a very small area of the ball. Also doesn't keep it from rotating when trying to mill it off center.
If your glasses fog up and you want to make your own mask fans, here's how;
"My happiness doesn't depend on anything. My heart is always happy. I do have anger issues though."