Ah, contacts are in and I can see the world and posts in much better clarity
For 18" and hidden you can still use lightweight drapery hardware like you would use to hang a small set of sheers and a wooden dowel. Everything would be readily available at your local hardware store. Tip: When cutting wooden dowels wrap a piece of tape around the area you are cutting and cut through it, that will reduce splinters and the chance of splitting the dowel.
For a non-hidden industrial look, you can have the dowel extend and use picture hanging wire twisted up at the ends and simply hung on a nail.
I have a friend who found some "day of the week" red work squares and simply hung them on wire coat hangers using some small clothespins she got somewhere, it was really cute. I've seen the small clothespins sold at party stores and used for hanging Christmas cards or other decorations on a string.