The rocket mass heater is definitely the real deal. Easily the most bang for the buck out of anything I've built. It's been working flawlessly for years now. I have to vacuum out the ash once a year and I do sweep the chimney but honestly I don't think its ever really been necessary. The most creosote build up I've seen was maybe 1/16-1/8in on an 8in chimney. Plus the exhaust gas is never hot enough to ignite it. I burn some punky ass wood in there too. I upgraded the insulation on the riser and rebuilt the burn chamber at the same time. A few of the fire bricks cracked, I think because I was burning it too hot at first. It really is a fantastic technology that anyone with the right situation to have one, should.

When it comes to manufacturing RMH, the core could be done but the mass probably has to be custom built. The core isn't really hard to build anyway and it's much more forgiving than the books make it out to be in my experience.