You may be like me and never heard of a rocket stove before. But I stumbled across this little gem when looking for something else on you tube. It is basically a very efficient little wood stove that is easily made using some very basic materials that are easily obtained. Typically tin cans. 

It is excellent for free camping as you can use leftover items and if you are handy with some tin snips you could make one up quite easily. 

My one was made using some more elaborate materials that I had laying around.

Basically, it allows you to use a wood fire heat source when their is very little timber around as it can run very efficiently and produce very good heat by just using sticks!!!

It is quite capable of boiling the billy or pan cooking. It's easy to light and maintain.

Rather than provide the long winded explanation of how it works and how to make one on his forum, visit you tube and look up rocket stove or try this link for a simple explanation and images. http://www.theresilientfamily.com/2012/04/rocket-stove/

Here is mine made from a paint can, some scrap steel tube and pearlite for insulation (available at Bunnings in the garden section). It works a treat!!! (That's steam from the water boiling, not smoke)