I remember being at a huge toystore somewhere when I was about 12 years old.. it was amazing, they had multible huge lego displays that where perfect.
Including one featuring a then new underwater theme with divers, but also including boats with cranes, diving cages, etc.
It was pretty much under a square glass box, in the middle there where lots of rocks and all around where the divers, fish, underwater laboratory and such, and above those rocks they had a glass plate. Above the glass plate there where boats, and they even made something of a dock with diving equipment.
It's probably the most elaborate display I ever saw in a store, and they had several such displays. Sadly only of lego though, but I never saw anything like it before or after in any toy store.
Either way that glass plate seemed to work perfectly for it, it was light blue glass even. I'd bet that with glass and see through paper or plastic it could give an even greater result.
