CNC machining allows for high accuracy and excellent surface finish and/or details. CNC machining is the Economical for small to short run of production parts that require wide range of operations to be performed. CNC machining no need to compromise with raw material because parts can be machined directly out of engineering plastics and metals. Generally large and bulky parts are economical by cnc prototyping compared to Rapid Prototyping processes because most of Rapid prototyping proprietary materials are expensive.