Some Hardware stores (like the OSH near my home) sell Reflectix by the foot. No need to buy the whole roll.
I have also used the padded mailers that some companies ship small goods in as material for a cozy. Cut to fit a quart-sized Ziplock and tape the edges with some packing tape.
Also, since Mountain House freeze-dried dinners come in lightly insulated foil envelopes that are designed to be employed as "one-time-use" cozies, why not simply reuse a washed out one as a super light and cheap cozy? A person could slip a quart-sized bag of food inside and use it repeatedly, then throw it away at the end of the hike.
Just a thought…
Michael


