The successful design and manufacture of today's increasingly complex engineering products relies to an ever greater extent upon the production and communication of information. The majority of design research to date has concentrated on supporting the information-rich latter stages of design and concerned itself with the distribution of product descriptions for the embodiment and manufacture of products. The conceptual stages of design, typified by vague knowledge and shifting goals, have been excluded from the research investigation. While computer processing power, storage facilities and organisational capabilities could prove useful within the early stages of design what tangible evidence do designers produce that could be captured by digital techniques? This paper studies designers at work in the early stages of design, concentrating on the visible sketching component of the design activity so that it might be understood and its efficiency subsequently improved by computer support.