At the prototype stage, casting is performed from a 3D printer that does not require a mold. It is possible to test under the same conditions as during mass production. After that, when the shape is fixed by trial production, a mold can be created and the mass production system can be started as it is. Since the manufacturing method is the same for prototype and mass production, there is no need to change specifications or design, and smooth transition is possible. In the case of machined products, we can handle everything from trial production to mass production, just like lost wax, but since we do not make dies, there is the problem that it is difficult to obtain cost benefits during mass production.