As mentioned in an earlier post, Best Glide has some neat tins for storing equipment. Another site you may consider is bepreparedtosurvive.com. They have lots of interesting items and storage containers of various sorts that might be of interest.

An additional storage container for treating water might be something to add to you small kit. A large oven bag for roasting a turkey packs down really small. If you cut it in half it'll compress to the size of a condom, but much more durable. You can pre-measure it and mark it with a Sharpie for convenience.