Wouldn't it be nice if you could go backpacking for a week and be able to have an ice cold soda on that last day? Or to keep sausage and eggs cold for longer? Well for the total cost of less than 10 bucks you can! This is a cheap and effective DIY. The whole thing weighs barely anything even with 3 ice packs, you'll definitely be carrying more weight from the food you'll be keeping cold rather than the cooler and cooling packs themselves. This project will take you an hour or so and the payoff would still be worth it even if it took 10 hours.
Step 1: Materials
The materials in the picture are:
2 Thermal bags that I found at the dollar store, you can also find them at Costco and just about any supermarkets though.
Mylar emergency blanket, you can get 4 for $5 online or get them at Sport Chalet or any other camping supply store.
Cold packs, You can get the particular ones that I use from doctors offices who have medication delivered that needs to keep cool, or you can probably buy them at Costco or any supermarket, I like these ones because they keep cool longer than the plastic ones and they can be shaped by freezing them in whatever position.