Image made by a computer aided design (CAD) package of a generic modern car. The image is in the form of a wire frame drawing, where the surface of the vehicle is described as a set of interlocking polygons. CAD is an increasingly powerful tool in the design of many common products, as design changes may be quickly incorporated into the model. Pre-computer age techniques involved the labour-intensive carving of wooden mock-ups of designs from paper technical drawings. CAD packages may even be integrated with production machinery in computer aided manufacture (or CAD CAM) systems.