Job? I see no need for a post retirement job.
But, I do want to volunteer as labor, in a variety of fields. Stone masonry would top the list. Lots of things can be learned in a book, or a video, some things must be learned by doing. I can mix mortar, and stack rocks, and in fact have. But there's nothing like having someone pick apart your work as you do it to improve how you do it.
So for me, I'll be using my labor to pay professionals to improve my skills in areas I want to develop. But that's hardly a job. Internship, that's what I am thinking about. I don't want to apprentice, I doubt my interest will last that long. But 2-3 weeks hauling rocks is likely to teach me everything I want to know about it.
Each time this comes up, author is a popular choice. Not for me, but for those who are interested, Scott Alexander, from slate star codex wrote and published a book, unsong, at
The book was very good, but I really liked the way he did the editing and publishing. I feel like ebooks are an adaptation of an old publishing model using new tech. This is more of an organic, fresh approach to the concept of publishing in an age of information.