Not to toot my own horn, but I've actually thought of doing this exact thing, I didn't ever DO it... but it has crossed my mind in the past. Okay, that was totally to toot my own horn. Maybe I'm a little jealous that somebody else did and posted this before I ever got motivated enough to even buy all the supplies. Although my idea involved a balloon, I think I like the ball one a bit better as it gives you a rounder shape.
Anyways, click the picture above and hop over to Crafynest blog for this tutorial!