I had been bothered that rocket stoves were being imported from China. See here. They are made of steel, packed with insulating material and the heavy end product is being shipped over an ocean propelled by diesel. And they were then subsidised by an NGO with funds from overseas and distributed to the poor. It still cost a Rs.1,000.
I sat with potter Ramalingham of village Dargas, about 15km from pointReturn. We discussed an alternative. After three iterations, mostly to get the height right, developed the above. It costs Rs.120. One encases it in mud to insulate and the rocket fires. I have three working now.
A feature article on this appeared here