Wanted to brag about my new portable Rocket. It's nothing earth-shattering but being portable is very helpful for demonstration purposes. Plus the stovepipe flange on the side of the drum makes it really easy to plug into a bench or 50 gallon drum bell or chimney. The core is a 6" from DragonHeaters http://www.dragonheaters.com/?a_aid=industrialrustic (yes I am promoting them). It's in a TractorSupply Job Box full of vermiculite.
My pie came with a little toothpic holding up this tiny ad:
Switching from electric heat to a rocket mass heater reduces your carbon footprint as much as parking 7 cars