Krylon paint is my friend.
One of these days I want to paint or cover a few different size balls to use as art in the garden. I plan on looking at yard sales for used beach balls, bowling balls, basketballs ... whatever I can find. Even a tennis ball could be painted or embellished for garden art! These are bowling balls, but check out some of these great pictures:
http://www.google.com/search?q...
And, here's a tutorial from awhile back on the Garden Art Forum:
The thread "Bowling Ball Garden Art Tutorial" in
Garden Art forum
This is a bowling ball I covered with flower photo's from a magazine. I used Mod Podge to glue them to the bowling ball and then sprayed it with a clear sealer. It held up for only about two years in the intense Florida sun but I plan on re-doing it some day ... and I have another bowling ball that I want to do cover with mirrored glass or something.