A flame in the cold

"What would we do without the artificial fires? There is no wood to burn, and the parts of animals that can be turned into fire stink and leave soot behind. Besides, there is nothing more beautiful than to lie with a loved one covered in fur before the fires. How many children would have never been born without them?"
-unknown
"When I was a young boy, I always told my brother I'd have to take his toy pixie away, so we could feed the flame. I don't think he ever believed me, but started hiding the little thing nonetheless."
-Varshk

Inventor(s)

Presumably, when the world was frozen the ancestors came up with the idea for it. It's made of metal, so they must have acted quite fast, if you believe in the story of Nushta.

Access & Availability

There are over a 100 smaller ones available for the village that can be carried around. In the homes of the ancestors, they are suspected to be there, but it's not exactly known if they are in the walls, under the floor or anywhere else.
The smaller ones are usually borrowed from one of the home of the ancestors, since they are stored there.

Complexity

One can only imagine what mysteries hide in those little boxes! If a button is pressed, a fire appears, that crackles and looks like a real one. You can touch the flames without getting burned though, yet it still gives off heat.
Even more mysteriously, it never needs materials to keep it going and not even the elders can remember a time where the fires have not worked. Jokingly, some people say that pixies power those fires, since it's the only magical thing left in the world.

Discovery

As far as the natives know, the ancestors made them. They have always been there and hopefully always will be, since life might be impossible without them.