Austin Kleon on using your books as time capsules. I try to do a similar thing by using postcards, ticket stubs, restaurant cards, etc. as bookmarks and leaving them in the book when I finish. https://austinkleon.com/2020/01/29/how-to-turn-your-books-into-time-capsules/
Sunbeam City is a Libertarian Socialist solarpunk instance. It is ran democratically by a cooperative of like-minded individuals.