a method of forming thermoplastic panels is disclosed which includes the steps of forming the thermoplastic panels by extrusion or a similar process and simultaneously or subsequently texturing or graining at least one face thereof , and utilizing such pre - textured or pre - grained panels to form a finished panel or article by disposing such panel in a thermoforming mold having at least one grained or textured mold surface against which the pre - textured or pre - grained surface of the panel is disposed and thermoforming such panel . the process provides a textured or grained surface having greatly improved uniformity and enhanced appearance .