Well, I know, publishing your own book sounds like vanity (or desperation!) but I don't see it that way.
When I grew up, 'proper' books were hardback - selected by editors you went to university with, published by your old school chum, then sold to, and read by, your peers.
The whole paperback revolution made all sorts of other books available and accessible, from popular science to pulp fiction. People could afford them, you didn't have to treat them with reverence (students scribbled in them, used dayglo highlighters, etc GASP!), and could easily give them away and get another copy.
Well, paperbacks come as standard now, and hardbacks remain a luxury item for most people.
Many of us now spend as much on a magazine as we might have previously on a book.
So, to avoid trashing the planet unnecessarily while still ending up with something you can read in the bath or on a train (without battery failure) or in bright daylight (sunbathing on holiday) a hard copy still makes sense. And Print-On-Demand makes even more sense to me. It should become standard, somewhere in the future, rather than swamping the planet with paperbacks which end up remaindered and then pulped.
So making this first book remains playful learning to me. I may have something more to say later, I may spend more time on writing and editing, but this got the ball rolling for me.