Freestytle sells two different varieties of black plastic canister for 120 films. I have stocked up a bunch of them to contain exposed (and unexposed for that matter) film. Lately I've been putting a piece of masking tape on the top with the film type written in. After finishing the film, I move the tape down onto the side so it sort of locks the removable top as an indicator the film is exposed. Size-wise, I prefer the one that has a hinged flip-up lid, although I suspect the other variety with telescoping screw-together sections may last longer.
The last trek where I took a dozen or more rolls, I prepared some zip-lock bags with a folded hunk of black construction paper inside and buried exposed rolls in my (carry-on) luggage. I believe Lowepro or one of the bag makers sells a softsided bag designed to carry quite a pile of film, also.