I've designed a tee based on a sound hole that's available in black and white. It's intended to be a subtle design that will be recognised by other players but not the rest of the world.
More info this way...
http://ukulelego.com/articles/ukulele-go-sound-hole-tees/
More info this way...
http://ukulelego.com/articles/ukulele-go-sound-hole-tees/