This paper attempts to clarify a design process that is being used by Kazuyo Sejima and Sou Fujimoto based on the use of scale models. Two typical cases are studied and represented graphically in order to map the workflow. The results reveal that the mutual influence between team members, the continuous process of production and selection are closer to an "editing process" rather than the conventional linear design process. The architectural quality and character of the work produced by Sejima and Fujimoto can be seen as a consequence of the process itself. The process based on the use of scale models becomes an object of design, and its advantages and disadvantages are discussed in this article. This systematical study is expected to offer new ideas to practitioners on how to integrate scale models in the design process and how to enhance creativity and collaborative teamwork.