The special tool manufacturing industry is faced with accelerating world competition coupled with a demand for higher quality, shorter delivery times and competitive pricing. To help meet this challenge, greater productivity improvements in tool design must be made. The researchers hypothesized that it is possible to transfer the design skills of a tool designer to a parametric design system that would automate the design process. This removes the tedium of tool design, allowing the designer to focus solely on verifying the final design. This hypothesis was tested through the development of a parametric design system which automated the design of countersink cutting tools and generated the NC code for machining the tools. Given four basic parameters of the tool, the parametric design system draws a 2-D representation of the tool displaying its features and generates G code routines for machining the tool. The system was applied by a local tool and fixture manufacturer. Results showed that the system reduced the manufacturer's design time from 2 hours to less than 1 minute. Machining of the countersink tool has been reduced from approximately 8 hours to less than 4 hours. © 1996 Taylor & Francis Ltd.