I found and old shelf made of spools and small lengths of wood when cleaning out my parents old smoke house. It may have been made by my Dad when a child or who knows.
Its very simple-
As a base 4 large spools had a heavy piece of wire strung through them--4 corners--a loop had been made at the bottom to keep wire from sliding out-
Then what ever size shelf you want-have a piece of 1/2 x however long you want piece of plank wood, holes are drilled in spot where wire can run through-
Next-you can use as many spools as you want for the height of the shelf--low shelf use about 3-4 spools stacked--with the wire running through them. Keeping it all tight to prevent wobbling.
Continue on up for however high you want. At the top and end of wire-place another spool and again loop off the wire to secure---Then paint or paint the boards only to show off the spools
You would need to hang using long nails or brackets to hold up on the wall under one of the boards. you really cannnot sit shelf flat, unless you can figure out something.
My Dad was born in 1919-so you can imagine how old my shelf is. A little summer arts and crafts for the kids!