Cardboard Protection?

[spykitten.livejournal.com]

I'm making boxes out of old record covers (the most basic box - just cut, fold, glue). But I'd like to cover them with a protective layer. I was thinking of painting the cardboard Elmer's Glue, because it dries clear, especially if watered down. Or how about Mod-Podge? It doesn't need to be really heavy-duty, just something that will be a little glossy and keep them from getting too banged up. Thanks for your ideas!!