The notion of collaborative service was firstly used by Jegou and Manzini in 2008 to discuss how services based on a tight collaboration between providers and users and based on the sharing of material resources, knowledge and competences, could support the transition towards more environmental and social sustainable ways of living. Since then the attention towards services characterized by sharing and collaboration has been growing quite quickly in the (service) design field. Yet, they entail a number of questions in relation to how to design for them, as well as in relation to the collaboration between the designer and various other stakeholders. To navigate this rich complexity we propose the two notions of commons and infrastructuring, and we do that by reflecting on the case of designing a makerspace, Fabriken, a sharing-based collaborative service. We use the notion of commons as a framework to articulate the organizational forms and decision-making structures of these services as well as highlight some of the challenges they entail. Particularly, we focus on the challenge of openness, and how this might be addressed through the presence of a “partner”- a mediator that supports sharing and collaboration when participation is transient and participants have diverse interests. With infrastructuring, we want to provide instead a particular understanding of how these services may be designed highlighting how they require the alignment of both human and non-human actors, and an long-term effort that goes beyond the “design-time”, in the “use-time”. Infrastructuring is not solely driven by the designer but yet, the nature of these services require to carefully consider designer’s agenda.