Long, narrow sheets of plastic are sometimes also referred to as strips. Such plastic strip varieties are often placed in doorways for climate control purposes in industrial settings and even in public places. Most other plastic strip varieties are characterized by length and narrowness. They are used as building trim, components in furniture, collators for nails in nail guns, vehicle trim and for many other purposes. Rigid plastic strips can be made from many plastic materials. These include high and low density polyethylene, PET, polystyrene and many other plastic materials. Each material is chosen based on its qualities of strength, durability, weather resistance and other relevant qualities. PVC, for example, is often chosen because of its resistance to UV rays.Plastic strips are manufactured by a process called extrusion. Extrusion is a continuous plastic fabrication process, which makes it especially suited to the creation of long plastic strips. At the beginning of the plastic strip extrusion process, a collection of raw plastic material, usually in the form of flakes or pellets, is placed in a hopper suspended above an extruder. When the plastic is released from the hopper, it enters a conveyance channel where a large shearing screw forces the plastic down the channel as it turns. As the plastic moves down the channel, the friction caused by the turning of the screw causes the plastic to become molten. Some extruders will feature electronic heating elements to aid in the plasticization of the material. By the time the plastic reaches the end of the channel, it is ready to be formed. At the end of the channel is a die, which is a specially designed tool that turns raw materials into useful products. In the case of plastic extrusion, a die is a metal plate with a specially-cut hole through which the plastic is intended to pass. As the plastic is forced through the die, it takes its shape. When it emerges on the other side of the die, it is a newly extruded plastic strip. The strip is then allowed to cool and harden, after which point it is cut to length and either sent for shipment or prepared for additional processing like painting or labeling.