A towel, it says, is about the most massively useful thing an interstellar hitchhiker can have. And there is even a way to make it slightly more useful. This towel messenger bag is not only good to avoid the gaze of the Ravenous Bugblatter Beast of Traal, but you can also use it to carry around things.
Surprisingly, all you need is a towel (and some thread). Depending on the towel size, you might need a second one for the belt. Or simply use the belt of a bathrobe. The towel I used was about 150 cm x 76 cm. The piece I cut out for the bag was 95 cm x 45 cm, which left me with enough fabric for the belt. Doing it again, I would recommend using a belt from a bag you don’t want anymore. That way, it might even be adjustable.