A method of forming an elongated trim strip product by first extruding a first strip of thermoplastic material from a die having an outlet with an area at least substantially as great as the desired cross-sectional area of the strip product in planes perpendicular to the direction of extrusion. Immediately subsequent to the step of extruding and while the extruded strip is still in a plastic state, it is passed longitudinally between cooperating forming rolls to shape the cross section of the extruded strip to the desired shape and cross section of the strip product. While the extruded strip is passing between the cooperating forming rolls, a backing strip of foil or thin metal is directed between the rolls in alignment with the extruded strip to bond the backing strip to the extruded strip.