In general, the design process consists of three stages, namely, “Analysis,” “Synthesis,” and “Evaluation” as
shown in Fig.1 [2]. In the first stage of “Analysis” basically, the composing elements of the subject manner are
clarified by dividing it into details. In the design activity, this is the stage of “functional analysis” for grasping
customers’ required functions. The next stage of “Synthesis” is for integrating plural elements. In other words, the
vectors of thinking are oriented to the product as a whole. In the design work, this is the stage of creativity by
considering the means to achieve the required functions and integrating the elements to create conceptual design
proposals. The last stage of “Evaluation” is for selecting the optimum proposal out of several choices. In terms of
mode of thinking, Convergent Thinking is applied in the Analysis stage, Divergent Thinking in the Synthesis stage,
and again back to Convergent Thinking in the Evaluation stage. In this way, creating the optimum product design
drawing by effectively switching between convergent and divergent thinking is the ideal way of design activities