I use old blueprint cabinets. They look like this :
They're fairly cheap to come by. Because ever-since the era of computerization, No one is saving their old blueprints anymore. They're all digitized these days, so the only time const. Co's need these, is for current in-the-works plans. Everything else (for archiving needs) is digitized. So you can sometimes pick these up cheap.
Shadow boxes fit in them perfectly. Only something very big (like cannon ball, etc....) would be too big to fit.
And then I have each drawer themed with different type objects, or drawers for specific sites, etc....