Copyright law forbids the creation of derivative works (excepting any region-specific fair-use rules) so you're only allowed to create them under the rights granted to you in the terms of the license - thus under this particular license you can't make commercial use of derivative works.
But 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.
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.
> What if I take the design, print it, include the thing in a staged photo, and sell prints of the photo?
Probably fair use, provided the design wasn't the main focus of the photo, but merely part of the "set dressing."
> What if I skip the printing and use the design files as a basis for a rendered photo or animation?
> What if I print the design, then use a 3D scanner to recreate a file from the physical artifact?
Those questions are simpler - both scenarios would be derivative works of the original files, so covered by the license.