Air Dry Clay is non-toxic and is mainly used by crafters, artists, hobbyists and children above 8 years old.  It comes from real Earth Clay, is a bit heavy in weight, but unlike the Polymer Clay, no oven or klin is needed.  Water can be added to soften or join pieces.  One can use most traditional clay sculpting techniques with this type of clay.  The wet clay takes impressions well from rubber stamps or textured materials.  Thoroughly dry pieces may be painted with acrylic or tempera paints.  Normal shelf life is about 2 years.