The process of extruding has been compared to squeezing toothpaste from a tube where the paste takes the shape of the tube opening. A billet of heated plastic is placed in the extrusion press and is forced under pressure through a die. The die may contain one or more openings having the desired finished cross section. Limitations on length of parts are the result of the weight of the extrusion billet and/or capacity of the down stream extrusion equipment. KEYWORDS for this process: tubing, extruded shapes, extruders