last couple of months I spent quite some time on creating a small e-book about creating add-ons for Blender and I am happy to announce that it now available from Smashwords. (and probably soon from Kobo, Apple, etc)
It is a primer so it won’t cover everything there is, but it should you started on creating add-ons that provide all sort of functionality, up to creating meshes with vertex color layers and even parametric objects (that save their options along with the object so that you can tweak them at any later time).
You need to have some experience with Python and because there is a lot of information packed in a small volume you do need to invest some time: learning to create Blender add-ons is not rocket science but there is a lot to learn.
Anyway, the link provides access to a free sample as well so you can have a peek beforehand to see if it interesting.