Repurposing scrap iron.

[CJ1]

That is one of the more simple ones I've seen made. They work very well for storing in your car or something in case of an emergency.

 

[sumi]

That's brilliant!

 

[CJ1]

I've seen others made out of soup cans and paint buckets with Some, heck I can't remember what it's called, to insulate it. But making them is a little more labor intensive.

Here is one where they used what looks like fine gravel. But gravel is heavy compared to that other material that I can't seem to remember right now.

 

[MoonShadows]

OK...pardon my ignorance, but what is so great about rocket stoves? I have heard they burn hot and don't produce much smoke at all.

 

[CJ1]

You are correct. They don't produce much smoke because there is almost complete combustion. That means you are getting more bang for your buck. Smoke is basically unburnt combustible material. Since it's more efficient you end up using less wood to cook your food. Less heat is wasted. And they're easy to make and portable.

 

[Britesea]

I think the insulating stuff you are thinking of is vermiculite or perlite?

 

[CJ1]

That sounds right thank you.