Rigid and flexible expanding urethane foams are available in a variety of densities. These cast-able urethane foams will expand to many times their original volume when mixed. They have been developed for a variety of industrial and special effects applications and the foam products can be pigmented to achieve various color effects. The rigid foams are especially useful as reinforcement for hollow castings. The flexible foams are strong, versatile and ideal for arts, crafts, industrial and specials effects applications including padding/cushion material and gasket material.