I will be experimenting with a new round tin which used to contain milk powder and is more or less air tight and waterproof. It is a milk sample tin from the milk company (they hope for me to recommend the product to my patients).
You could probably fit quite a fair bit of PSK equipment inside and have a nice compact waterproof kit which you could cook boil water in. Somthing like the 'you CAN survive' tin.
See the pictures below.
Inside is a Huntman Lite SAK for size reference: