Sheet extrusion is the process of producing a continuous single, or multilayer gauge sheet made typically of a thermoformed polymeric material. An extruder, consisting of a barrel and combination conveying and mixing screw, forces the material through a slot die. The material is conveyed through rollers that keeps it flat as it is cooled. The resulting sheet is then trimmed and cut to a desired dimension, thermoformed into various hollow shapes, or spooled onto a roll.