Abstract: Thermoplastic parts are formed by a process that produces at least one surface that is a direct replication of the mold surface without secondary operations, e.g., a "Class A" surface. The process is particularly suitable for the production of large parts such as automobile panels, refrigerator panels and the like especially those employing a high-viscosity resin and particularly those parts made by blow-molding. The process comprises pressing at a selected pressure a plastic preform heated above the glass transition temperature (Tg) against a suitably smooth or detailed mold surface held at a temperature below the Tg of the resin; raising, preferably rapidly, the mold to a temperature above Tg for the time necessary to raise above Tg a depth of resin sufficient to remove surface imperfections, die lines, and pores, and fill voids, and substantially embed included matter; and rapidly cooling the mold until the molded part is below Tg when pressure may be released and the mold opened.