A FIRST EXTRUDED STREAM OF MOLTEN SYNTHETIC THERMOPLASTIC MATERIAL AND A SECOND EXTRUDED STREAM OF DIFFERENTLY COLORED MOLTEN THERMOPLASTIC MATERIAL ARE COMBINED IN A CONDUIT TO PROVIDE A COMPOSITE STRATIFIED STREAM HAVING ADJACENT DIFFERENTIALLY COLORED LAYERS EXTENDING LONGITUDINALLY OF THE STREAM AND HAVING A RELATIVELY SHARPLY DEFINED INTERFACE THEREBETWEEN. THE COMPOSITE STREAM IS IS THEN PASSED THROUGH A SHEET FORM EXTRUSION DIE HAVING ITS DIE LIPS GENERALLY ALIGNED WITH THE AFORESAID INTERFACE, WHEREBY THERE IS PRODUCED COMPOSITE SYNTHETIC THERMOPLASTIC SHEETING HAING A VARIEGATED COLORED PATTERN, ADVANTAGEOUSLY A WOOD-GRAIN TYPE PATTERN, ON AT LEAST A PORTION THEREOF. THE PATTERENED EFFECT IS ACHIEVED BY CONTROLLING THE TEMPERATURE OF EACH STREAM OF THERMOPLASTIC MATERIAL T PROVIDE A DIFFERENTIAL IN THE ADJUSTED MELT VISCOSITIES OF THE MOLTEN SYNTHETIC THERMOPLASTIC MATERIAL AND/OR THE RELATIVE OUTPUT VOLUMES FOR THE INDIVIDUAL THERMOPLASTIC STREAMS BEFORE COMBINATION.