Artistic grade plaster strips. You should be able to get them at Michael's or a craft store. It only takes about an hour to make, so you still have time! Use petroleum jelly on your belly -- and also, I had my dh and bff use saran wrap on my boobs so they wouldn't sag.
You can also pm Noelia, she gave me info on where to buy -- but I bought on eBay and it took like a week to get here.
My dh did fiberglass on the back of my cast to reinforce it, after it was dry.
To paint, prime it, and then use regular acrylic paint.