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someone ought to do a comparison that includes just using 2 or 3 rocks in a mini horseshoe vs store bought stove and see if its worth it.    [/quote]

I have done that when I can see that my fuel is going to run short before trips end. Even with a small fire the water will be boiling very quickly. By having the rock tripod to the side of the main fire coals can transferred to keep the heat you need for whatever you are cooking. Advantages: no space, no weight and no need to pack extra fuel in case you figured wrong. I like to keep on top of the fuel situation and have these fires when the wood is dry and conditions are safe.