Simultaneous product development, which involves early consideration of all areas involved in the production process, is an effective means of reducing costs and development times while increasing product quality. To achieve these goals, Martina Bock has developed a problem-oriented expert system shell for design. The shell is characterized by a modular nature, ensuring the flexible application of the system in various fields and for different products. The functionality of the shell is demonstrated in the important sub-aspects of cost-effective, manufacturable, and quality-oriented design.