YouTube. Pizza oven full build from Australia. Good molding and casting form ideas. Uses crushed pumice stone. I don't know how expensive that is in the US. And I don't know if it's healthy to cook right on hot cement....? I would make a hybrid of the typical American oven using clay and fire bricks, but add some vermiculite to the mix, and definitely use his molding and casting techniques. Oh, except for the ball. A wet sand mound seems much easier to me.