Low buck projects- Let's see 'em!
I've found boxes unsuited for small curved spaces but bags are too floppy. A great middle ground is a rectangular cooler bag. It's just stiff enough to hold its shape stay open and make finding its contents easy but easily stuffs into lockers and odd spaces. I have 4 or so of them to store engine parts, electrical supplies and household supplies.
On clearance at the end of the summer they are about 10 bucks each.