At the core of education, engineering, and science lies the quest to better understand and improve the world. This document aims to explain the essential role of open-source hardware for this mission and why it should be considered an essential pillar of the ongoing open science programmes in Dutch Universities. Open-source hardware is hardware whose design is made publicly available so that anyone can study, modify, distribute, make, and sell the design or other hardware and products based on that design. Ideally, the design of open source hardware is available in the preferred format for making modifications and uses widely available components and materials, standard processes, open infrastructure, unrestricted content, and open-source design tools to maximize the ability of other individuals to make and use hardware. Open-source hardware gives people the freedom to control their technology while sharing knowledge and encouraging commerce through the open exchange of (compatible) designs. Open Science practices are becoming the norm in academia, and are rightly encouraged by funders and policymakers of higher education. Open-source hardware is an essential pillar of Open Science. Sharing hardware designs openly both enables more people and teams to access it, and through encouraging replication it makes science more reproducible. But it is also an area of contention because of the exclusive knowledge transfer practices and (not always justified) confidentiality clauses in research partnerships or contract defaults. Beyond academia, open hardware has the potential to radically transform science, education, and society by facilitating collaborative innovation and democratizing access to technology. It can massively accelerate the transition of an invention into a useful product, and simultaneously reduce costs and promote sustainable practices. By promoting open-source hardware initiatives, the Netherlands can solidify its position as a leader in Open Science and contribute to the global effort of achieving the sustainable development goals.