I have a small rocket stove project in mind that I'm trying to make without buying anything, so, using only components in my household. Our soil has a good percentage of clay, so I'm gonna be using cob, but I want a way to test what mixtures and additives have the best insulation properties of the materials I have access to. Shredded paper? Cut grass? Husky fur, because our dog is shedding this month? Something else I haven't thought of yet? I don't know what would be best, and I would have fun testing it.