Now, what is interesting is if someone were to blatantly violate the license and start manufacturing commercial keyboards. I believe their only recourse would be to revoke their license of the design files, and then it would be copyright infringement. The thing is, I don't know how copyright law would handle any damages.
I don't know if making a physical product could be a violation of copyright, regardless of if you had a license to use the design in the first place. I could definitely imagine a company trying to enforce this, and a judge throwing it out because it should have been handled with patents.
Again, not a lawyer, just speculating on a forum.