The commitment of the Fab Lab community to participate in processes of commons-based knowledge production thus also includes global knowledge sharing. For sharing back into the global commons, new knowledge needs however to be documented in a way that allows to share it by the means of information and communication technologies. So far, there are no empirical studies that provide insights into the question whether and how knowledge is indeed shared globally in the Fab Lab community, and how the above mentioned challenges are experienced and dealt with by the Fab Lab members. This paper reports an empirical study that aimed at closing this gap based. The study was based on qualitative interviews with sixteen Fab Lab users. In these interviews, the responded seventeen projects that were analysed as case studies. The case studies revealed, that knowledge sharing is not impeded by the barriers discussed elsewhere in literature such as motivational or technological impediments. Nevertheless, the cases showed that global open knowledge sharing was far from the norm, and sharing remains mainly local and personal.