Das Air Dry Modeling Clay
This is a natural modeling clay that air dries to rock-hard density. It needs no baking, is break resistant, and can be painted or varnished (you can use acrylics and/or Sculpey glaze). It's the perfect consistency for molding and isn't very messy so it's perfect for all kinds of projects. Available in 1.1 and 2.2 lb packages and comes in terra cotta (reddish natural color) or white. Non-toxic.