I like Otterboxes or the smaller Pelican cases. The Nalgene bottle is a great idea. It may be a bit hard to get the FAK contents out if you cut yourself then try to get stuff out while applying direct pressure to yourself.

I also have some FAKs using an Outdoor Research zippered pouch that has a mesh pocket on one side and the other side has a fold out organizer kind of like a mechanics tool roll for wrenches. I havent seen that model pouch for awhile. It has great access for a lot of small stuff. The big downsides are that it isnt rigid to protect the contents like an instant cold pack. And that it isnt waterproof if you get caught in a downpour.