How would these discs work? Would they just be retextured books or have additional functionality?

I have an idea as to how this could work.

Music discs for music books are registered in a database sorta like the mapart db. A one time fee has to be paid to "press" a music disc from a book (book isn't used up in the creation of the disc).
Discs can be bought from the database for a set price by it's creator (locked to nation capital shop plots).
The redstone signal output of a disc can be adjusted by the creator and is displayed in some way(useful for redstone application).

Maybe something similar to the art plugin where you can store your music and pop them out whenever. You could also turn them into vanilla discs to avoid plagiarism.