Based on a 3D model generated in a CAD system, a rapid prototyping system can manufacture a prototype in few hours. The most common techniques for rapid prototyping use materials like resins and polymers. The difference between the material of the manufactured prototype and the real piece makes the realization of some tests with the prototype almost impossible, such as analysis of mechanical and chemical resistance.This work proposes a technique to make a prototype by machining it using a 3D machine. The great part of the industrial machining can be realized using 2½D machining. Some authors proposed methods to machine the sculptured surfaces in a 2½D machining; however, the surface finishing, depending of the application, is not so good. We proposed an algorithm capable of generating the toolpath for a 3D machining to attend this demand.