Making models in the traditional way demands considerable manual skill and dexterity, for example cutting wood parts with a razor knife. The advent and adoption of rapid prototyping and manufacturing (RPM) machinery has made it possible for ordinary designers, students, and even children, to produce physical artifacts using computational means. Although most RPM hardware is as simple to use as a printer, the software tools that designers use to produce representations for output require a great deal of expertise. To produce a 3-D model designers must create a computer graphic representation. Typically designers do this using powerful general-purpose CAD modeling.
