Sadly the CC BY-NC-SA license is not an open source license, other than that I'm quite happy to see this project, besides still needing HP cartridges.

What do you mean by "open source" in this case? The OSI's definition? "Open source" as a stand in for free/libre as the FSF defines it? Something else? I'm wondering what the material difference is between your definition and the project's.

OSI, of course, they coined the term.

The difference is that open source software/projects must allow commercial use.