This paper proposes a novel methodology, QFD based 3D morphological charts, to support variant design of simple and technically mature products. Customer’s requirements are incorporated in developing the morphological charts through a holistic approach, One-Step QFD. In contrast to the traditional cascading deployment, members from marketing, design, and manufacturing teams concurrently derive the requirements from three different aspects. The charts driven by the deployment results produce design concepts of high feasibility through query by function, specification, and module of a product. They are presented in 3D assembly for better visual stimuli rather than clutter of 2D sketches. A computer-aided conceptual design system is implemented to realize the proposed ideas with computer mice as an example product. A design experiment is conducted to compare the quantity and quality of the concepts generated with and without the aid of the system. The results show that it promotes quick generation of innovative concepts while maintaining their manufacturability.