Marketed crocheted balls are always covered in wool. If you now stick a piece of velcro hook under your jacket, you've got a holder that will never fail. OK, it does tend to pull at the yarn a bit over time. But these balls do have a tendency to go fuzzy.
If you go to the trouble of having the balls crocheted, I would suggest you use cotton and not wool. The grip is better than wool, and the balls never go fuzzy. However, now the velcro holder doesn't work.
It's all swings and roundabouts.
Bye for now
P.S. Jim, if you're ever looking for cork balls, you can get 1/4", 3/8", 1/2", 5/8", 3/4", 7/8", 1", 1-1/8", 1-1/4", 1-3/8", 1-1/2", 1-5/8", 1-3/4", 1-7/8", and 2" balls from The Cork Store