This is how I made the shelves in my cargo trailer conversion both attractive and functional. They are also nearly bulletproof.
The bungee I used in this build is from www.qualitynylonrope.com. I only used this because it is what I happened to have at the time. It is good quality so I recommend them, but shipping is slow. Below are some links to others I have bought that are the right size. I also provide an amazon link for the aluminum extrusion I used as well as mustache wax! LOL
Shock Cord (Bungee):
https://amzn.to/3hewHpSAluminum extrusion:
https://amzn.to/3aDzdUk. They dont have flat bar that is clear anodized, so for that nicer finish you will need to cut it down from angled aluminum. If you are good with a mill finish, just get it at home depot.
Mustache Wax!:
https://amzn.to/2Qi0anb all links are affiliate links