In recent years, the number of new organizations aiming to accomplish principles of sustainability has rapidly grown, leading analysts and scholars to announce almost a new industrial revolution. An example of this is the proliferation of the so-called fabrication laboratories (FabLabs) that nowadays are perceived as being forerunners in innovative and sustainable high-tech production through peer-to-peer collaborative practices and sharing. However, the challenges managers face in translating these promotional aims into organizational action is vastly understudied. To address this research gap, we have studied the management of two FabLabs, in Italy and Finland. In this study, we draw from a psycho-sociological framework applying cultural-historical activity theory, and especially from the concepts of activity system and contradiction. According to this perspective, a sustainable organization is based on promotion, enrichment, regeneration, and flexible change efforts, and it is related to the managerial and ability to bring internal and external stakeholders together to recognize and solve tensions and contradictions collectively. Through our case studies, we have provided new research knowledge on how managers make an effort to translate sustainability into action in the complex context of FabLabs, involving multiple, often competing stakeholders and activity systems. Our analysis reveals multiple tensions in the collective activity, stemming from system level contradictions, which represent a challenge for the daily work of the FabLab managers. In the paper we also suggest how an engaged management orientation towards sustainably can be promoted, and we discuss future research topics.