alt Hacker NewsBut is a physical item a derivative work of it's technical specifications?
If the design files qualify for copyright protections, then modifications to them would clearly be derivative works.
I don't think it is clear if the keyboard itself would be a derivative work, as it almost certainly can't be protected by copyright. This is what patents are for.
Ianal, usual disclaimers, etc.
The design files don't qualify for copyright protections, they describe the design which (maybe) qualifies for copyright protections.[0]
The artistic design of a specific keyboard can certainly be copyrighted, but not the functional nature of it.
[0]The exact wording might be protected, but not the factual information contained. Sports scores, or say measurements of a keyboard, are not copyrightable items as they are just facts, though their presentation might be.