Air dry clay is a plastic mass made of water, microspheres, polymers, glycerin, and pigments. It helps develop attention, fine motor skills, and thinking. It is sold in airtight packaging because it can harden when exposed to air at room... temperature. As a result, a lightweight, durable substance is formed, comparable in weight to foam. The colors mix easily with each other. It is elastic and strong, very light. The clay does not stick to hands, tables, or clothes. The finished craft hardens in the air.