This towel holder can be used for towels without a strap.
You should print the parts as you see them on the picture, brim is recommended, especially for the hook. It should be fine without supports, but I've used some supports on the hook part, because it snapped for me few times without them while printing. I made the hook thicker after that, but still used them just to be safe.
The author hasn't provided the model origin yet.