My co worker welded together this rocket stove from some scrap metal the other day. I've heard the term before but didn't really know what they were. Looked online and saw tons of different shapes designs and sizes. Pretty cool idea. He wants to make a miniature sized one for me because he knows I like camping. Idk if a 2-3" pipe would get enough airflow though. I think this one is a 5" pipe. I would think they would get more sensitive the smaller theyre built.. this one seems to burn good and boils water quickly, as long as the wood is dry and smallish. Would be fun to keep in the backyard whilst doing yard work etc.. could keep warm by it too.. kinda like a burn barrel but with more character.
I personally would go with 6” square or round as that’s the standard starting point for most serious rocket stove enthusiasts. I’m not saying smaller is no good, just staying within studied/analyzed parameters.