In this world I'm creating, humans are shrunk down to 2 centimeters tall, and have been teleported down to an earthlike dimension consisting only of insects, plants, fungi and other invertebrates. The landscapes are mostly mountainous, but the general crust layer of the world has about the same contents as on earth, so ores like iron, copper, as well as aluminium rich ores, like bauxite are still found everyehere. There are also deserts and soils that contain rich amounts of metals that would maybe be more useful than the large ores deep underground to humans that size.
As for the square-cube law, the dimension only protects the humans, but as for important details on heat and hydration, they do need to eat cavern fruits to stabilize their nutrition and metabolism (a few handwaves there).
Though when it comes to receiving heat energy as radiation from above, it's much more dangerous to them. So a simple flame from a match might as well be as dangerous as a star.
Now they have been living in this dimension for a few generations starting from stone-age scratch. The humans have already gotten a well-held grasp on surviving in their varied biomes, but one of the humans has discovered the iron pellets from the dirt he gathered could theoretically be morphed to create solids that would greatly benefit their survival as a civilization.
He proposes to his government that there may be a way of "manipulating" these iron pebbles to not only create pure sting proof armours, but also as tools and potentially more options on construction. But the local engineers who have been carving structures with wood, wax and stone warn him that such a project could potentially be way too dangerous and may take too many resources to be worth the investment, because the heat energy required would be like trying to construct a volcano or nuclear reactor that could easily go into meltdown. The local engineers may have a point. But the government decides to see if they could anyway.
Which method could these humans use to smelt and create blacksmiths viable enough to smelt not just iron, but other metals like copper, aluminium, etc. to solid shapes they can further use?
Answers need to include possible safety measures or equipment they would need in order to prevent themselves from burning up from all that radiation.
Just for physics' sake, a match would burn at about 800 degrees Celsius. Iron melts at 1500 degrees Celsius, so I don't know if they need to be close to a volcano or just create a campfire that would titan their size in comparison.
I would imagine such a construction project could dwarf the pyramids, by comparison, to just smelt a few grams of iron. Or is this too much?