This is small potatoes and maybe not exactly what this thread was intended for, but on the subject of making money with hobbies ....
Over the last two or so years I've been dabbling with sewing stuff for cash (and occasionally trades). It's "go out for burgers" money, not real money.
My most consistent money maker has been a cover I make for a device for cleaning vinyl records (Record Doctor V). I've sent them all over the US, Canada and as far away as Australia. The machine doesn't come with a dust cover, and apparently vinyl record enthusiasts REALLY don't like dust!
This almost certainly won't ever be a real business, and my day job is too good to think about quitting, but it's nice to do something I enjoy and get a little spending money out of it. I have five sewing machines, and they've all paid for themselves - largely because part of the hobby for me is buying really cheap vintage machines.
I also run a YouTube channel that promotes the idea that sewing is a manly pursuit that is often overlooked, and is a useful skill for us guys (especially us car guys!) to possess. Anyone interested, check it out at
https://www.youtube.com/user/thejasonofalltrades