The next time you go to the local box store, look for items sold in rather square or rectangular clear plastic containers. Or check out the kitchen isle and look for measuring jars with flat sides.
Seems like I've seen mixed nuts come in clear squarish containers, I know the local Menards had bungy cords sold in clear containers...I'd bet Hobby Lobby has what you need, I'm thinking ,cheap model car display case...heck, you might even need what's inside...lol!
Of course, the old fashioned goldfish bowls with two flat sides might be the quickest and cheapest bet.
