In hardware shops one sees a wide variety of systems for hanging shelves on walls.
However, as far as I can find out, this system "doesn't exist already". [I did a rather cursory Web search - and the 'Bakery search is broken.]
The loop-hung system should be cheap, and adaptable to bearing light
or heavy loads.
Visualise a wall, interior or exterior.
Find firm fixings for a spaced row of screws/screw-hooks, even nails, appropriate to the weight etcyou want to store.
Prepare by knotting or whatever, a loop of rope. cord, surplus cabling etc. for each hook/screw/nail, ... but each loop will have to be of exactly the same dimensions.
This will be the hard part I suppose. but I can see a way of doing it.
Anyhow, the final step should be simple ... put a loop on each hook and insert your [suitable] plank/shelf through all the loops.
In my mind's eye I see the weight of the books/paint-tins/objets d'art, converting each loop into a self-locking triangle.
These days my mind's eyes work as well as ever, but my real eyes are a feeble substitute.
I couldn't even make those exactly similar loops or shop in a relaxed way for a version of the materials to match our battered "eclectic" furniture.