Rolling cutter bit design is an iterative process in which a designer must balance bearing and cutting structure components within the available space to satisfy specific service requirements. In the last ten years bit designers have exchanged then-drawing boards for CAD terminals. While traditional CAD has a positive effect on the design process, custom software written to address specific design functions has been the key to realizing maximum benefit of the technology. Utilizing programs written in a modem graphics interface language, bit designers are able to consider more design concepts in the initial design process, select from existing tooling for manufacture, and fine tune or revise designs quickly. Specific details of the implementation of CAD at one rock bit manufacturer are given. Problems in implementing the system described and their solutions are also discussed.