I noted the comments about using a Pelican case for a first aid kit. True, they are strong dependable cases, but to cut weight and make better use of space, my FAK is packaged in good ziplock bags and placed into a soft zippered case. If you need first aid the bottom of the pack for the FAK is the worst place to put it.
Incidentally, my FAK can handle the common minor cut or burn, but also more significant trauma and with all the components, still does not take up very much space.