I was thinking what a small container would be. Foil is a good idea. I had thought of an over bag and some Aquamira tabs. Also you could probably get a fresnal lense in it.
Thats a great pocket kit! You should check out the Olight I3E EOS flashlight. Its about twice the size of the one you have in there but its super bright and a very capable light. Takes 1 AAA and the light only costs about $10.
Pretty cool kit. Great idea on the foil. Have you seen the thick plastic water bags wazoo sells? They are really well built. Keep up the great work my friend