Three years ago, I built a Sioux-style teepee here in my yard as a gathering place during our long, cold winters.  Using a modified version of the "half-barrel" method posted here: http://www.youtube.com/watch?v=x3tAn3wcWkE , I was able to build in a below-grade circular mass bench and rocket-stove. Construction of the stove and mass bench took approximately 3-4 days working mostly alone--with some cobbing help from my wife.

It was important to me that the fire's LIGHT be visible within the teepee, since the ambiance of a fire is nearly as important socially as the heat!  This led me to the batch-load design, which sacrifices some efficiency to the loading door and the viewing windows.  Happily, these efficiency losses result in very rapid heating of the teepee's air space, so that it is possible to be warm in the space in a shorter period of time (when starting at -30 degrees, it takes appx. 2 hours for the bench to hold heat).

Before this winter comes, I will be "building up" the mass bench so that it has a back-rest around the entire teepee circumference. This will also mean that I will be able to LIFT the entire teepee another half-meter to provide more headroom when standing.)

-Tim