FYI, in case anyone is intimidated by the above construction, you don't really need such a production to enjoy a rocket stove. I made a table top sized one from sheet metal, I spotwelded it but it can be made w/screws or careful folding of tabs, or a reused can of substantial size like below. It is also great camping, has a little grill on top, can boil 1 liter of water with 180 grams of sticks, and makes for very consistent results.
at home it sits on a couple bricks on a metal porch table for cooking chunks of what-have-you, or just a quick fire fix.
this isn't mine but its about the same size, I don't have the extension, just a grill a couple inches above the inner can outlet