In this paper, an ergonomic product design process was constructed. The unique part of the proposed design process are first, Hand-on design and 3D graphic design are combined each other. Second, iterative design process was used to refine the product surface representing human 3D body surface. In result, the curvature of the toilet seat could well represent the real human body surface when using the proposed process
compared to the 3D graphic design process only, that was expressed graphically in this study. Thus, such design method has increased the quality of the product as well as consumer satisfaction.