you need to insulate the burn tunnel and riser, hint - insulative materials are usually very light in weight.....do a search for papercrete/paperclay ceramics or insulative refractory....
From the picture i notice that you have a short exhaust? Notice that in a rocket mass heater a lot of the heat is taken out through a long exhaust tube, the barel is not all the heat transfer surface. For trying it, it is ok.
Stinging nettles are edible. But I really want to see you try to eat this tiny ad:
grow your own garden and build your own home, in Montana, for free-ish
