Messy Birthday Party For 11 Yr Old Girl

I am throwing a messy party for my daughter`s 11th birthday party. We are having it at home, and I am looking for some ideas for games. So far I`ve got shaving cream slip and slide, pie fight, making goo, making toothpaste putty, chalk painting on a giant banner, worm dig(digging out gummy worm out of choc pudding with hands behind back), silly string fight, water ballons, sprinkler. Anyone have any other ideas? I am going to have plain t-shirts ready for the kids to slip on and the kid with the messiest t-shirt at the end of the party gets a prize. We have a snow cone machine-a small one and we are going to set it out in the backyard(it has a safeguard, so the kids can`t hurt themselves) and the kids will be able to put ice in it and let it spray out and have an ice fight. I`d appreciate any new ideas. Oh, for the cake, I am going to make a small one that will be decorated nicely for blowing out the candles. Then I am going to make a really large sheet cake and cover it with white icing. Then I am going to make bowls with different colored icings(I will make this icing thinner) and the kids will get to use paint brushes and paint the cake!