Any hobby/project ideas that result in something useful?

So I really want to find more things I can do that are both fun and interesting but also useful in some way. I have a hard time actually focusing on stuff and finishing projects and stuff if they don't actually result in something useful. So I really want to have something useful out of it in the end. I also don't really want anything that requires me to buy a bunch of things up front because there's a very good chance I'm just gonna be left with useless materials that I'm not gonna use again. I like the idea of sth that at least at first either doesn't need materials (sth digital for example) or uses (at least mostly) materials I already have.

Some things I like and already do sometimes is sewing, both making clothes from scratch but also a lot of modifying or fixing clothes, which i like cause it's useful and while it does require materials rn I do already have them and i can also use old clothes and stuff which is good. I also draw sometimes, mostly just digitally rn, which i like cause bc its digital it's free but it doesn't really result it anything useful.

One general idea I had is something to do with electronics or programming. I've done some stuff with arduino for classes before, as well as other programming, though only a little bit, and i do like it. I like that i'm learning things and i need to use logic to figure out how to do things. But I'm not sure what I could do with that that would actually be useful. Also obviously I own a lot of random materials for arduino stuff already so that's nice.

I really want to make something useful for myself and ideally do so using either no materials or materials mostly already own. Any ideas like that would be great!