Plastic ship model kits typically provide thread in several sizes and colors for the rigging. Automobile kits typically contain vinyl tires, although sometimes these are molded from polystyrene as well, particularly in very inexpensive kits. Thin metal details produced by photoetching have become popular relatively recently, both as detailing parts manufactured and sold by small businesses, and as parts of a complete kit. Detail parts of other materials are sometimes included in kits or sold separately, such as metal tubing to simulate exhaust systems, or vinyl tubing to simulate hoses or wiring.