Find some thing you enjoy creating digitally and just do that and publish.

Straight ort is probably toughest to sell, but ... if you enjoy it, one day there might be enough fans to sign up to patreon, buy your prints, book, e.t.c.

Like, you are probably choosing the Brandon Sanderson route, "Even if I never publish any of these novels, and I will die with 20 books worth of written stories that almost nobody knows about, it was still worth it!" As late sit pterry said, "Writing is the most fun you can have by yourself." You probably won't become next Sanderson or next Weir (Martian was self-published as a web-series) ... I would think that if you find your audience, you could become someone like qntm?

Also, books that teach about stuff have easier time finding an audience.

Especially if you already have a hobby that you can write about. This is the thing, you need something you are excited about or at least persistent about doing. My partner has been training dogs for over a decade, and writing training plans is not as lucrative to have as the main income, but it scales better than training in person, right ;)

Simmilarily, you could make games, publish them on itch and probably won't become next Maddy Thorne (of Celleste fame) but you could become new Brozef (look up Felvidek, it started as his university ...thesis? I think? And now it is like a game on steam and people even bought it!)

Boardgames/tabletop can be a thing - itch can work there too, but there might be a local game jam where you could cobble something together and then somebody might print&play it?

People still like to get ~human made assets. 2d art. 3d models. I used to faf around in blender a decade ago and even I heeded the siren call of a well rigged character for 10$ :D

Yeah ... reading this after myself - you are thinking the wrong way around. You need something you are excited about or at least persistent about doing. If you have several, yeah thinking about which one is more commercially viable can be good. If you have something concrete in mind, that is like a project that is good too, but you should be honest with yourself if you really need the money, or if this is a "eh, could be nice if something comes out of it, but it was time well spent even if not"

Ask HN: Low entry barrier hobby that can potentially generate income?