We, at JSP Corporation, have developed a blow foaming method, which is the direct blow molding, suitable for large moldings, such as automotive applications. This method is a combination of multilayer molding based on our original co-extrusion technique, and extrusion expanding. It can produce multilayered expanded parisons and their moldings. Using unique expansion technology and a volatile physical expanding agent, we provided an expanded layer with a lower density, compared with well-known blow foaming methods using decomposable chemical expanding agents. It can be molded through a single process, adding to products values, such as lighter weight and higher thermal insulation and cushioning performance. In addition, the resulting products are highly recyclable because all layers are made from a single material.