Abstract Selective openness allows a firm to sell a systemic innovation that combines both open and proprietary technologies. Such firm strategies are now common for open source software and other information goods. However, they pose conceptual and practical uncertainties for hardware-focused companies, particularly as research on open hardware has emphasized community rather than firm success. Here we study firm openness in 3D printing, with a case study of how MakerBot Industries leveraged external communities and selective openness become the consumer market leader. After reviewing the literature on systemic innovation and selective openness, we document the proprietary strategies of a dozen startup companies during the first two decades of the 3D printing industry. We contrast this to the open hardware, software and content strategy that MakerBot's founders used to enter and grow the consumer market from 2009 onward. We show how MakerBot shifted to a selectively open, systemic innovation strategy that complemented proprietary hardware and software with open user-generated content from its Thingiverse online community. From this, we suggest the inherent complementarity of selective openness strategies between open and proprietary components, and conclude with predictions as to when and how a startup or incumbent firm will combine open and proprietary elements.