In October 2015, we convened a workshop for 80 researchers and practitioners involved in makerspaces in Europe. Our aim was to explore how makerspaces can help cultivate sustainable developments. This paper reports workshop discussion and ideas on the topic, and illustrates interest in the deliberative potential for this kind of ‘citizen lab’. Interestingly, given the emphasis on tools and making practices in many makerspaces, discussion at our makerspace event focused much more on community development capabilities and skills for mobilising alliances for raising social awareness. Discussion problematized different kinds of sustainability, noting that social and economic ambitions can potentially align well with environmental goals at this level of activity, but are not always designed to do so. At heart, the workshop revealed the need for strategies that counter the incumbent social structures that influence ostensibly ‘open’ makerspaces, and thereby enable the tools and capacities available to work on more sustainable developments.