An approximate design system is developed to design a free-form surface combining developable surfaces. The cost of construction may be reduced using developable surfaces, while maintaining the architectural characteristics as well as the mechanical performance. The proposed system is composed of a series of operations: (1) forming an initial shape and determining a target free-form surface, (2) geometric approximation of the free-form surface based on the combined developable surfaces, and (3) minimizing of the strain energy of the combined developable surfaces. The performance of the system is demonstrated through examples of a roof shell and a free-form facade.
