Assuming the Heatsheet is to be used in a emergency situation, I don't really understand why you would really need to find the perfect container for it. Mine came in a sealed vinyl pouch which sounds adequate enough?

I can easily imagine myself tossing the Heatsheet out after use, or if it's still usable I'd try folding it back and just store it in a sandwich size Ziploc and put a rubber band around it.

My 2 cents.