This paper describes the development of a model for classifying the different type of ‘design demonstrator’ that might be used in translating scientific activity from the laboratory to the market. Two detailed case studies are described in which designers worked closely with scientists. In one of the projects, the scientists were seeking to commercialise their research. In the other, the research was at an early stage and the scientists had not considered commercialisation. Different types of physical artefact produced in these collaborative projects were analysed to identify the extent to which they might contribute to science, technology, application or market. Evidence indicates that demonstrators might fulfil multiple purposes and that the translation from science to market is more complicated than is often shown in linear models. An original classification of the role of demonstrators through this journey is provided.