This paper follows recent science studies in theorizing information technologies as socio-material configurations, aligned into more and less durable forms. The study of how new technologies emerge shifts, on this view, from a focus on invention to an interest in ongoing practices of assembly, demonstration, and performance. This view is developed in relation to the case of the 'prototype', an exploratory technology designed to effect alignment between the multiple interests and working practices of technology research and development, and sites of technologies-in-use. In so far as it is successful, the prototype works as an exemplary artefact that is at once intelligibly familiar to the actors involved, and recognizably new.