A neat combined oil lamp / emergency space heater, using simple tools and readily available materials...
Good examples of the old oil lamps used for thousands of years. Remember 2 things. They burn oxygen and they are burning. I would not use one in a tent unless it was in a bucket with sand in the bottom and that I knew there was some air circulation. If SHTF, it might be handy to be able to burn cooking oil, or you may want to eat it. It is a good use for rancid, bad, oil. Do not use kerosene or gasolene for the fluid or you will have your own personal Molotov cocktail and that is a no no in your house when lit. Hard to knock success as it was the only lamp light for a few thousand years.
