I used old bank statements and other paper destined for the burn barrel. It's a great way to recycle.
For the second layer I used brown paper bags. On Stoll's site he gives all sorts of basic how-to information. It's a pretty flexible craft, in terms of glue to flour ratios and types of paper you can use, but we'll see how the actual painting part goes. Painting requires artistic ability and could very well be a disaster for me. Anyway, it's so much fun. I love papercrafts and rarely do anything sculptural that isn't modular (ie: folding the same model over and over again). Tonight, I paint. Wish me luck!