Thought they were cool. As I should, I tried to make some of these about 6 years ago. Talked with a manufacturer and everything. I was going to use a springier material (think more like those supper-balls from the 70's with glitter in them). In the end, there was no way for me to make them and not go broke or charge way too much.
FFWd to this summer, I bought a variety and put them on many of my machines, ranging from '79-'96. That was about two months ago.
I think they are beautiful, however, I am not satisfied how they play (for many of the same reasons posted in this thread) Oh, one of them snapped into a noodle after less than 10 games.
This week I started to take them off (which was harder than putting them on!) and gave a way my first pair today for my friend to try without spending the bucks.