I saw one of these online. This is simple and there are many versions , some improved.
This can be made in different ways.
This might be useful in an emergency to survive. Be careful of burning anything inside, including candles.
I believe it is designed and based on the heat holding and heat release properties of ceramic and metal.
An ancient tek - a clay pot radiant heater.
edit - sitting here in an ice storm freezing rain looks like a sheet of glass outside. I am lucky I provide for myself so I lack nothing. smoking some cannabis spending time here watching the day go by. I am fortunate.
Edited by Heirloom Spores, 16 January 2017 - 02:56 PM.