Abstract: A process, apparatus and product related to extrusion or other deformation of solid thermoplastic polymers includes using a die or other deformation devices that have an interior passageway of changing cross-sectional shape commencing with an inlet of compact cross-section and ending with an outlet corresponding to the angular shape of the final extruded profile. The die passageway is divided into at least two consecutive stages including a first stage having an interior contour adapted to transform the polymer billet at a low deformation ratio into an intermediate cross-sectional shape proportional in shape to, but greater in cross-sectional area than, the final angular shape and a second stage having an interior contour adapted to transform the intermediate shape to the desired final shape with substantial longitudinal orientation of the polymer, but without substantial lateral shear deformation.