Below is a list of Urethane Casting manufacturers from Grand Rapids, Michigan. Urethane casting, technically referred to as polyurethane casting (or PU), is an elastic polymer, or elastomer, containing urethane carbamate links. From a molten liquid state, polyurethane may be fabricated or molded into low-density flexible foam, low-density rigid foam, soft solid elastomers (gel) and hard solid plastics. Valued primarily for its uses in rigid and flexible memory foams, polyurethane is extremely useful in solid plastic form as well.