A method of molding, from porous material, a low-density product having an impermeable surface. A mold is provided, which has a cavity, the outline of which defines the outline of the product. The starting material is a flat sheet of plastic foam. The first step of the process, in some cases, is a pre-heating procedure, which softens the material. Then, from this sheet there is stamped a blank having substantially the outline of the desired product, which is then inserted into the mold cavity. The mold is then heated with the blank therein to form the blank permanently into the desired product, after which the mold is quenched in cold water with the product still inside. The product is subsequently removed from the mold and frozen. The result of this molding method is a low-density product having an impermeable surface integral with the foam interior which is suitable for receiving various types of brightly colored finished. It is also contemplated that a non-porous plastic film may be molded in place on the surface of the product.