If you want open cases your best bet is to just buy a bunch of garage shelves locally or if you want specifically designed aluminium frames then you can also order the parts locally cut to whatever sizes you want them with corner/elbow elements.
Or if you really want to done it cheaply, just get some thin wood (batten?/slat?) and build it yourself.
Thank you for the suggestions but if I wanted to do it myself, I would've done it myself. I have more than enough to do with my other companies so I don't have time to start building cases for mining. Time is money.