How to convert mp3 to a beautiful audiobook? You need:

  1. a folder with mp3s tagged (whatever tool, on windows it could be mp3tag.exe)
  2. if you want chapter images insert that in tags, each file a different cover
  3. add a file cover.jpg to your folder, as a main cover of the book
  4. get m4b-tool as a command-line tool

navigate to your folder and run:

❯ m4b-tool merge -v "./" --output-file="./audiobook.m4b"

It will scan files, convert them, merge them, maintain tags, add chapter for each file, add cover and everything. This tool has a lot more to offer.