Rocket mass heaters can be build and sculpted with recycled and natural materials. A rocket mass heater offers great efficiency, artistic freedom and allow you to build your own with just basic construction knowledge. Find out more at www.naturalhomes.org/permahome/rocket-mass-heater-basics.htm
Rocket Stove Mass Heater. "heat your home with 80% to 90% less wood; exhaust is nearly pure steam and CO2 (a little smoke at the beginning); the heat from one fire can last for days; you can build one in a day and half; folks have built them spending less than $20"
A cob bench isn't the only thing a rocket stove can warm up for you. This is a rocket stove powered staircase, sculpted out of cob by Danish architect, mason and thatcher Flemming Abrahamsson [www.fornyetenergi.dk]. It's included in the book 'Rocket Mass Heaters' available here www.rocketstoves.com by Ianto [www.cobcottage.com] and Leslie [www.well.com/~les/].