Makes sense, presumably if the project is well enough supported then they can move on to cartridge/head production, or modify to use whatever heads are available.
Out of ignorance, I wonder how IPR will work with interoperability rights. Patent rights seem like they might not be exhausted when you buy a spare part to use in third-party device, vs when you buy a spare part for an OEM device.
I'm guessing all the tech here has aged out of patent protection though?
The rest of a printer aren't too hard to design and make, especially if you don't have super tight budget constraints.