While traditional science, technology and innovation (STI) policy has emphasised protecting intellectual property through patents and copyright, evidence suggests these tools may not optimally serve both innovators and society. Alternative innovation approaches based on openness and shared technology are emerging that could better address societal needs while supporting more sustainable production. We examine the development of 3D printing technology, where the expiration of key patents enabled a dynamic, open innovation ecosystem. This open-source approach has led to new forms of collaborative organisation around shared designs and resources, facilitating broad technology adoption across diverse communities. Analysing these practices through the lens of digital commons practices, we explore how they enabled alternative business models in 3D printing, while acknowledging tensions with dominant market structures. We propose an STI framework based on the commons that prioritises social and environmental benefits in alignment with post-growth values.