Abstract
In this paper we present some reflections stemming from a case study aimed at building a socio-technical infrastructure for supporting participatory design and development. We summarize and abstract our experience into an hourglass approach defined by the intersection of two co-evolving dimensions of infrastructuring: the social and the technical ones. Different subsets of the community, characterized by the increasing involvement of volunteers, position themselves along the two axes and have different roles in the design and use of the generated artefact