Geometric modeling technology has been widely used in the development of plastic products. However, due to various reasons, the technical data that mould makers get from clients is not the CAD model, but the physical samples consisting of complex free curves and surfaces. If using the traditional method to design and manufacture product, the cycle time is long and the cost is high. It is unable to cope with the ever-changing plastic market. Reverse Engineering, at this time, comes to solve this problem. Therefore, as a new discipline, reverse engineering has attracted more attention. 

The traditional design is based on function, to turn product into reality through scheme design, pattern design and product manufacturing & assembly. Reverse engineering design is to measure contour of the physical existing samples accurately and quickly by using 3D digital measuring instrument, especially to measure the sample with complex and irregular surface. After editing and modifying, the coordinate data is transferred to the general CAD/CAM system, and the original object or image is transformed into a 3D digital model on the computer. Then CNC machine is to make the required mould, or generate STL file. Finally the samples are made by rapid prototyping.