This paper deals with the potentialities for do-it-yourself (DIY) labs to open up the research and innovation system to citizen participation. DIY labs are spaces where academics and civil society stakeholders can gather to experiment with alternative research and innovation practices. I hypothesize that these collaborative practices are facilitated by intermediations. My results draw on the literature and on extensive field work in French DIY labs, also called fablabs, (bio)hackerspaces, makerspaces or third places. First, I discuss the relationship between DIY labs, epistemic communities and citizen participation. Second, I compare two situations of collaborative practices in maker communities. I show that managing the inclusion of non-experts in these technology-oriented communities requires a set of activities which need to be coordinated by an intermediary agent and are often distributed among community members. Third, I conclude that intermediations play a key role in transforming technology-centered into socio-centered DIY labs. In socio-centered set-ups, technical experts and practitioners from the groups concerned (users, patients, residents, etc.), collaborate thanks to intermediary agents. Intermediations are a pre-requisite for DIY labs to open up the research and innovation system to civil society.