@olmitch "open source" refers to the license on some source code or a development model, so I don't see any way to make such physical printer.

More details on the topic is: https://www.gnu.org/philosophy/free-hardware-designs.en.html

If you were to design a reliable printer that ran 100% free software and released the hardware design as a free hardware design and offered manufactured units for sale, you'll soon be attacked with patents by all the printer companies (despite how information on all basic printer functionalities have been publicly available for 50+ years, those companies have been awarded patents on basic printer functionalities).