Nothing!!! I had made way over 100 yo yo's because I wanted to make a quilt like one I had seen..so got on the band wagon and made all these yo yo's. Ended up tossing them out because I realized I was going to have to make thousands of them and I wasn't going to do that many!!!
I do have a pattern for a vest made from the yoyo's and if your interested in it, you may have it just pm me. :)