This is my very first design, therefore it could probably be improved. I made this to hook our Xbox controller clones into this very common shelve system I don't have the name for (see the photo). It probably won't fit the original Xbox wireless controllers, though, because of the battery case. Maybe it will still be of use to someone.

I printed this sideways in PETG, with supports. The latter tend to stick to the hook part, but as I said, I'm no expert. :P