There are loads of good videos on YouTube about how to make your own rocket stove, but this is how I made mine.
I used two catering sized vegetable oil tins and a normal baked bean size tin.
First using a strong pair of scissors I cut the top off the first large tin. Better to use tin snips if you have them but good scissors will do. Start the cut by making a hole in the can with a hammer and a sharp screwdriver.
Then I cut both ends off the second large tin and rolled it up to make a narrow tube. I used garden wire to hold it tight.
Then I took both ends off the small tin using a can opener, and using the screwdriver scratched a circle near the bottom of both the big tin and the narrow tube. The circle is nearer the bottom of the tube than the tin because the tube sits inside the big tin to form the flue.
I cut a circular hole in the big tin and the flue, and put the small tin through both. Then I filled in the outside of the flue with wood ash from my wood stove, to insulate it.
Finally I cut a hole on the middle of the bottom of the second large tin which was left over, and made a lid for the stove. I cut some 1cm notches in the top of the stove so the lid would push down into it a bit, and then hammered down the edges to keep the lid in place.
Finally I sprayed the stove black with woodstove paint. Voila!