Are nextruder nozzles even open-source??  

Are nextruder nozzles even open-source??

Hey.

I just got myself a new MK4. I knew Prusa was always commited to open-source so I assumed that the nextruder and the nozzles would be open-source as well. Are they though?? I can't seem to find any clones or nextruder-compatible 3rd party substitutes. The nozzles in the official store are ridiculously expensive and are not even available at the moment. I'm honestly baffled. I was used to the v6 environment which was full of 3rd party options for all the possible variations you can imagine.
I know there is the v6 adapter available (again, I can only find the official one on Prusa store) but it negates all the benefits of the nextruder system really.

So back to my question. Are the nextruder nozzles even open-source? It's already half a year from MK4 release and I can't seem to find any derivatives anywhere. Prusa being open-source was one of the main reasons I decided to buy into the ecosystem.