A successful prototype knowledge-based system has been developed for polymer composites design. This reporting focuses on the expansion and extension of the prototype. The expansion effort widens the scope of the system to include additional matrix and fiber constituents. Initially, the system designs a single composite material meeting the desired performance characteristics. The first extension effort involves modifications to produce a family of designs, presenting a more effective aide to composite designers. Another extension effort involves the selection of manufacturing methods for the composites produced. These improvements give rise to a design system that is approaching industrial level effectiveness.