As has already been said...don't get too caught up in the container. I've made kits out of all kinds of stuff...just to see what works best. My favorite is a soft case I got as a give-a-way at a meeting. It measures 2.5" X 4" and was intended to be a little first aid kit. I just added to the orginal contents.

I've also used tobacco tins, cigar tins, baggies, fanny packs, small plastic first aid kit containers and a floppy disc travel storage container (which works quiet well, I might add...it stays in a briefcase).