An integrated circuit (IC) design method for use as a design and/or manufacturing tool for designing and/or manufacturing integrated circuitry (110). The method utilizes one or more library element (150A-F) to provide a flexible modeling template. Each library element includes one or more module ports (160A-F) each for accepting any one of a plurality of device modules (170). The device modules are logical representations of corresponding respective portions of the integrated circuitry. For any given module port, the corresponding device modules may be interchanged essentially without additional integrated circuitry design changes.