After several years of development, complicated by the pandemic, disrupted supply chains, and war in Europe, we announced our new Original Prusa MK4 today. We began shipping the first units of the XL two weeks ago. There is an upcoming PrusaSlicer 2.6 with organic supports and many other great features. Our firmware team is finalizing the custom implementation of input shaping (vibration suppression) for the MK4 and XL. In addition, there’s the new MMU3, with completely rewritten firmware and tons of improvements.

The above and many other things we’ve been doing at Prusa Research for over ten years were only possible thanks to the great 3D printing community and open-source philosophy. However, the new printers and software releases have made me think again about the current state of open source in the 3D printing world. How sustainable it is, how our competitors deal with it, what it brings to the community, and what troubles us as developers. Consider this article as a call for discussion – as a kick-off that will (hopefully) open up a new perspective on the connection between open-source licensing, consumer hardware, and software development.

Before I start, I want to make a few things clear to avoid any misunderstandings:

• We stand by our roots in open-source and will continue to do so.
• Our desktop 3D printers will always be open source. We intend to continue publishing plastic parts, along with firmware source codes.
• We will stay open to third-party component manufacturers, accessories, add-ons, and unofficial upgrades.
• PrusaSlicer will always be open source.
• Our investment in PrusaSlicer and firmware development will continue at the same or higher level.

During the last decade, I have always been against companies that have turned away from the open-source community as time went by, eventually becoming closed-source. I don’t want Prusa Research to go in the same direction. Patents by big companies have limited the 3D printing world from the beginning, and projects like RepRap have helped it break out of that grip. When several important Stratasys patents expired in 2014, open-source development could finally take off at full speed.

Anyone developing something related to 3D printing today will benefit from more than ten years of continuous open-source development. Hundreds of individuals and dozens of companies contributed to getting the industry where it is today. The idea that you can develop a 3D printer with its firmware and software from scratch in a year or two is an illusion. We will always stand on the shoulders of people like Adrian Bowyer (founder of the RepRap), Alessandro Ranellucci (original author of Slic3r), David Braam (original author of Cura), Scott Lahteine (Marlin maintainer) , and many others. At the very least, they all deserve public recognition and thanks whenever someone uses their work. And that brings us to what worries me.

The open-source movement relies on the fact that everyone involved plays by the same rules. It cannot be done without mutual respect, understanding, and a shared goal. When someone suddenly bends the rules for their own benefit or openly violates them, the community makes it clear that it won’t stand for it. In the past, we’ve seen plenty of protests and boycotts that have forced even large companies to rethink how they treat open-source heritage. But in recent years, I feel that the situation is changing. More and more companies are breaking and bending the rules, and the community is not nearly as resistant to their actions as it once was. After a minor internet storm, the situation calms down, and the code remains closed (or only part of it is opened), and after a few weeks, everyone forgets.

In the meantime, I’ve been receiving information about companies that have started to apply for local patents based on open-source development and trademarks (you’d be surprised how many of them have “Prusa” in their name). About c