And you thought only ammo could be stored in these nifty vintage containers. Like 35mm film cannisters, the ammo can industry experienced a resurgence with the advent of geocaching. These cans are rugged, watertight (as far as I have seen), and hold tons of swag. Plus they are just plain cool.
The ammo can falls into the regular size category. Since they're pretty big (roughly the size of a larg shoe box) you can only really hide them in the woods, or at least in wooded areas. I have also found them under bridges.
I like ammo cans. Because of the size, they are easy to find and almost always have cool junk inside. Plus it's tough to hide them in urban areas, so chance of muggles is minimal.