Here's an overview of the project.

We are using an Adafruit Sound Board to store and replay the audio bits.  The board is very small and it can handle multiple audio files. Separate pins can be activated to play individual files (up to eleven).

Technical challenges involve creating an electronics enclosure and making photos/text adhere to the board material.

To create finished books that are reproducible, it will be necessary to find songs and produce audio tracks that are royalty free--so that's an intellectual property challenge.