Check out this mini rocket stove DIY

This is REALLY cool and totally doable by anyone. I'm thinking this would make a fun project to do with Scouts. Have to give it a try...

http://logcabincooking.com/hobo-tin-can-portable-rocket-stove-class/

They work, simple, easy, cheap(a hobo can afford one . But they will smoke a some and you have to tend them every 30 seconds or so. Four inch cans are better for the inner chamber and fuel input. Adding another can on top, double the heat risers height will get rid of most of the smoke. I have used one to camp with and cook on many a time.
https://lh3.googleusercontent.com/-FgCnDFjhhec/ULrQ94GmVGI/AAAAAAAAKq0/Q_7njMLAN-o/w607-h809-no/IMG++12-1-2012+2-42-35+PM.JPG

Well that's super cool too. I love these cheap on the fly rocket stoves!