The best part of 3d printing is making things you can't buy
I’m not very good with cad software but I love messing around on tinkercad and making little things to make my life easier. This week I made an under desk mount for my audio interface and I love it.
Wife got me into the hobby to go along with my other interests like woodworking and restoration, "something to keep him busy", but she’s a beast for scouring thingiverse and printables for stuff along with her own "what if" ideas. It’s great, sometimes I’m not interested in the object but getting there is so cool.
I think the most useful single thing I ever printed (also the first thing I ever designed in OpenSCAD) was the cat guard that prevents my furry friends from stepping on my computer's power button and accidentally turning it off. Never seen one of those in a store.