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?

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    $\begingroup$ I think it would be incredibly difficult for something like smithing to work when you have to take a disproportionately large distance from something 1000°C hot or hotter. I think the thermodynamics are very different on a scale that small. As an experiment you could make some tiny piece of iron 1000°C hot and place it 5cm next to an ant and see if the heat in that proximity kills the ant - i think it might, but i wouldn't bet on it. I just had one lecture of thermodynamics in my life and i am not that proficient on it. $\endgroup$ Commented Jul 3, 2018 at 15:18
  • $\begingroup$ @ArtificialSoul the thermodynamics are the same. It's the biology that is disfavorable. $\endgroup$ Commented Jul 3, 2018 at 15:33
  • $\begingroup$ @Renan, yes that is a huge problem anyway. There is a reason why we don't have mammals this tiny and no insects human-sized. But in regards of the thermodynamics i am not that sure. They are not entirely different, but i think that the ratio between convection and radiation are different. (radiation staying the same if all objects are proportionally shrinked, but convection is probably different if you have extreme temperature falls on a very small scale.) $\endgroup$ Commented Jul 3, 2018 at 15:51

7 Answers 7


Well if they follow a similar timeline to our own, they should master fire.

Otherwise they would start with the softer metals, like gold, copper, and silver. Using stone tools for mining and metal working. No need for extreme heat as these metals are soft enough to use tools to shape them. The metals would have more prominent features we wouldn't normally see unless we were up close and personal at the 2 centimeter height. But the size shouldn't be too much of a factor, since they're taking smaller metal and making smaller items.

Then after about a century start into lead, bronze, and tin. These would need higher heat, but over time with practice a community would develop through trial and error, a method to heat the metal into a useable state.

Perhaps some type of furnace designed into the stone around them with multiple tunnels specifically laid out to tunnel the heat in while filtering the radiation out, which is easier said than done and thus why they would need trial and error to come up with a system which wicks away the radiation to a safe location while tunneling the heat to a forge heating the metal.

Perhaps a furnace such as a single shaft with an opening at the top which holds radiation at extreme heat, and they build a swirling shaft around the center shaft, but with entrance at the forge. As it swirls around the radiation shaft it pipes the heat downward into the forge, with little radiation.

Everything following would need more efficient methods. After another century or so start into iron, mercury, platinum, and cobalt. Then after another century into nickel, tungsten, titanium, chromium.


Your tiny person will not find pellets of metallic iron in the dirt. Iron will rust on the surface.

But he might find gold, and even better, copper. The North American Indians (Mound Builder culture) extensively worked copper with no use of heat - all by cold hammering. https://en.wikipedia.org/wiki/Metallurgy_in_pre-Columbian_America#North_America

Here is a copper breastplate taken from a mound tomb in Georgia.


copper birdman breatsplate

So too your tiny people. They can work nuggets of copper and gold into plates using rock hammers like the Indians did. A tiny nugget will go a long way for an antsized person. No need for forges or dangerous heat.

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    $\begingroup$ A nugget would go a long way, but would they be able to apply the required forces to cold work it? $\endgroup$
    – Separatrix
    Commented Jul 4, 2018 at 10:36
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    $\begingroup$ @Separatrix put nugget at bottom of tall drop, spend 3 days pushing rock up big hill as a team. drop rock on nugget. repeat until done. $\endgroup$
    – J.Doe
    Commented Jul 4, 2018 at 14:48
  • $\begingroup$ @Separatrix Ant-sized humans would be proportionally much stronger (which is seen in the film Arietti) thanks to the square-cube law, which would help somewhat. Not for hammering directly so much than for building machines that can. $\endgroup$
    – Eth
    Commented May 13, 2019 at 10:34
  • $\begingroup$ @Eth, proportionately stronger only helps when the requirement is relative, here it's absolute. $\endgroup$
    – Separatrix
    Commented May 13, 2019 at 11:30
  • $\begingroup$ @Separatrix It wouldn't be to hammer it directly, but to build machines to do it. They would have a much easier time making a (proportionally) giant mechanical hammer than us, for example. $\endgroup$
    – Eth
    Commented May 13, 2019 at 12:39

Metalworking would indeed be a big challenge for a tiny race.

First, a forge needs to be big. We can not simply downsize a furnace and presume that it will build the same kind of temperatures, it will not. Blast furnaces are big even by normal human standards, for ant-men it will be bigger than Egyptian pyramids. Even small prehistoric forges would be quite big, though not out of reach for a determined community. To avoid coming close to fire, a system of control rods and pulleys can be constructed.

High temperatures in small volume can be reached via gas burning, however, constructing something like Bunsen burner from scratch may be even a higher challenge.

After "remote controlled" smelting forge is perfected, the next challenge is metalworking. A forge will be able to produce iron ingots. Turning these ingots into usable tools like swords or arrowheads will require extensive hammering. This is something that can not be done remotely using primitive technology. Tiny race's best option is to let those ingots cool down and then apply cold forging. A slow and difficult process for something like iron or steel, but totally doable nevertheless.

Next challenge is tempering. After cold hammering they may manage to produce a tool in shape of sword, but it would be a very poor quality sword. To improve quality, it has to be heated and quickly cooled down. This will again require a system of rods and pulleys, but is doable.

Overall, iron working is theoretically possible, but its level of difficulty will be comparable to the Apollo project for XX century humans.

  • $\begingroup$ It seems like bronze would be a better option than iron and steel for tools. Lower heat requirements, and easier to work afterwords (you can simply cast and then sand it into shape). $\endgroup$ Commented Jul 4, 2018 at 8:34
  • $\begingroup$ A blast furnace would be much much bigger than a pyramid to these people $\endgroup$
    – Separatrix
    Commented Jul 4, 2018 at 8:45
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    $\begingroup$ I don't think cold forging is doable here. Square-cube law works strongly against the ant-sized humans: the strength of the metal pieces goes up relative to the mass a hammer can have, so you won't be able to pack in enough kinetic energy to plastically deform it quickly enough. $\endgroup$ Commented Jul 4, 2018 at 9:49

square cube law works in your favor too, you don't need much heat for long to melt a tiny piece of iron. the real issue is you will have to heat the mold since the metal will cool VERY quickly.They don't actually need to handle the metal much size at that scale forging is basically impossible unless you work IN the fire. Handling for casting can be done at a distance with tongs and poles, the square cube law works in your favor again. A simple air draw will solve most of your radiation problems.

But you don't actually need to hot forge metal on that scale anyway, something like a drop hammer can stamp it into any shape you want even while cold. You only need heat for smelting,, and you won't be handling anything hot while doing that. Thankfully smelting actually works better on a small scale as long as you can keep the oxygen out of it.

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    $\begingroup$ Even though the metal would cool down very quickly, it might've not been that much of a problem for the tiny humans. Since they are small, they will move much quicker, perceive and think quicker, and therefore act quicker. $\endgroup$
    – A. Kvåle
    Commented Jul 3, 2018 at 20:32
  • $\begingroup$ there is not much reason to believe this, they might be marginally faster due to shorter nerve length. $\endgroup$
    – John
    Commented Jul 3, 2018 at 22:56
  • $\begingroup$ @A.Kvåle, this would not actually help even if true, heated metal is cooled by moving it in a forge, by reshaping it take a hot iron bar and bend it 90 degrees and will actually get colder, on a small scale there is no reservoir of heat, so shaping the metal cools it down almost instantly. $\endgroup$
    – John
    Commented Jan 17, 2019 at 20:33

Well, for one thing they could probably only wort with cold smithing in the beginning.

Next step would be to smelt the metal directly into the molds (aka. place the metal above/half in the molds and then heat the whole thing up in a giant furnace [which would be a pyramid-level project for Iron or so] However, there is stuff like Lead or tin, which melts at pretty low temperatures, and - while not useful for Armor or weapons - would be sufficient for most other applications. Furnaces for these could be mini-human sized, and due to the low temperature even forging would be possible (something that normal humans can't do since we have no chance of getting the point between melting and solid).

Also: Bronze would probably be the first real step. Real bronze smelter can be as small as 10 cm high, which would make it a big, but still realistic project for your mini-humans. [For this again the smelting-directly-into-the-mold approach would be the only way until some basic machinery is worked out.

[Assuming your humans still have some of our knowledge at least this should be fairly easy]


I can't offer much with actual physics but it occurs to me that the ant sized people may not need metals like steel. To something the size of an ant I would think any metal would seem fairly robust. Sure, if you scale up to normal size the lighter, softer metals are no good, but if an ant sized breastplate was made from gold or steel would it make much difference at that scale to its intended purpose?

  • $\begingroup$ Welcome to WorldBuilding chris! That is a nice addendum, but it would be nice if you could edit your answer to answer that question you've raised. Can you for example estimate very roughly how much force such a breastplate would have to withstand? That might shed some light on whether your proposed solution would work. Currently this looks more like a comment that is meant for some inspiration than a full answer of the question. If you have a moment please take the tour and visit the help center to learn more about the site. Have fun! $\endgroup$
    – Secespitus
    Commented Jul 5, 2018 at 7:04

The problems with using heat to form metals like iron are covered in other answers.

You might instead consider sidestepping the use of heat as your method of metal forming. If your race is able to create (or find) strong acids and also generate electricity they may use electroplating to create different metal shapes without heat. Electroplating uses acid to dissolve metals and then uses electricity to cause the dissolved metal to form on the surface of an electrode in the acid. The shape of the electrode determines the shape of the plating metal, so a breastplate shaped electrode would form a breastplate shaped metal object.

The acid could be found from the ants and beetles which use strong formic acid as an attack, so hunting for natural acid (if they can't manufacture it) could be exciting.

Electricity would require the ability to create copper (or silver) wires, but these metals could be formed with little or no heat.


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