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In my project, an Bronze-age alien civilization living near the coast has discovered a mollusk that can secrete ooze that later hardens into nacre, the same substance found in pearls. By using molds and the liquid secreted by these mollusks (let's say they are similar to Marine Pearl Oysters), they can create lightweight, strong solid objects and tools. Later, after developing the sufficient tech, this society then uses this material for 3D printing components.

My question is this: is this aforementioned liquid feasibly realistic? I know that nacre is composed of both calcium plating and a organic sponge-like layer, and that over time a mollusk can build up a pearl by applying layer after layer of calcium and organics, but can this process be liquidized, and if potentially so, can it be stored and used at will?

I am open and appreciative to all answers.

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    $\begingroup$ There's a considerable technological gap between casting/modeling and 3D-printing. $\endgroup$
    – Alexander
    Commented Feb 7, 2020 at 23:07
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    $\begingroup$ In the real Bronze Age, the substance which could be made a liquid, then poured into moulds to create solid objects and tools was . . . bronze. Bronze casting is known from the 4th millennium before the common era. (And lead. But lead worked only if the objects did not have to be hard -- lead is notoriously soft.) $\endgroup$
    – AlexP
    Commented Feb 8, 2020 at 3:18
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    $\begingroup$ @AlexP: Putting aside the idea that pouring suff into molds could reasonably be called 3D printing, people were doing similar things with clay & plaster even earlier. $\endgroup$
    – jamesqf
    Commented Feb 8, 2020 at 4:10
  • $\begingroup$ @Alexander I realize now that the disparity between 3D printing and molding may have been a overstatement on my part. The question has been edited to better reflect my line of thinking. Thank you for your feedback. $\endgroup$ Commented Feb 8, 2020 at 23:21
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    $\begingroup$ @AlexP While metals were certainly viable at this period, I would argue that the natural strength of nacre-based materials and the low-energy requirements required for the construction of nacre tools may have made it a competitive alternative to bronze. $\endgroup$ Commented Feb 8, 2020 at 23:23

4 Answers 4


Can the process be liquidized? I'm not a biologist, but I lean towards probably not.

At least. Not actual nacre.

Is "A mollusk that secretes a liquid that hardens into a solid object" plausible? Sure. There are a lot of things that are liquid and harden, many in the natural world. The issue you're going to run into is the hardening process. If the liquid hardens by itself, it will be difficult to store in a liquid state for later use. However, there's something that comes to mind that can solve this problem.

On my work table behind me, I have stuff for making dice. Part of that stuff is resin. It comes in two parts: The liquid resin, and the liquid hardener. When combined, it hardens into a very solid object.

So, the liquid that your mollusks secrete? That's the "resin." The hardener? Well, I'm also not a chemist but it could be something in its environment that causes it to harden. Remove the mollusks from that environment and they'll just make the liquid, which can be taken and stored. They probably need the hardener to do some natural things, but that can be controlled as well.

To use it, all you have to do is mix an appropriate amount of secretion with an appropriate amount of hardener, pour it into a mold, and wait. (Just a note, but this is not 3D printing, which is something that would be well beyond what Bronze Age could do even in a "Similar" fashion, but also well beyond anything they would need to do either)

Is this something that's likely to exist in nature? Probably not. Is something like this going to be a huge plot hole that rips people out of the immersion that the story builds? No. It sounds reasonable and really that's all you need for a story. Pretty much every fantasy, sci-fi, or even historical fiction novels have things that are way beyond this in terms of implausibility and we enjoy reading them all the same.

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    $\begingroup$ If the hardening agent could be salt, that might explain how it works for the mollusks. I don’t have enough chem knowledge to evaluate feasibility. $\endgroup$
    – SRM
    Commented Feb 8, 2020 at 14:28
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    $\begingroup$ Salt or salt-water would've also been my go-to for the hardening agent - it could in principle also make sense chemically (salts concentrations can change protein structures, some changes might be irreversible) $\endgroup$
    – Nicolai
    Commented Feb 10, 2020 at 10:31
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    $\begingroup$ @Andon your recommendation for a hardener has opened up a lot more potential than my original idea. I will gladly take your answer into consideration for my worldbuilding project. Thank you for your feedback, and have a good day $\endgroup$ Commented Feb 15, 2020 at 3:32

Storing the ooze maybe the simple part. Imagine everything begins when a fisherman who collected some mollusks for a meal lets some drops of the ooze fall on something like quicklime. Someone else notices that some marbles of hard material formed in the quicklime because it reacted with the ooze. Eventually they find out they can create the material by mixing ooze with the quicklime when needed.

It's the 3D printing that I see a lot more difficult, the tool maybe a dripping sack suspended to a bar moving on some tracks, but doing it manually is not only too coarse, it's a slow process that requires a lot of patience and those carrying out the work must be supported by the rest of the population in a period when people take a lot of time to extract food and resources from the environment. Maybe older slaves who can't do heavy work, but who don't need to eat a lot are turned into craftsmen doing a painstakingly meticulous job.

  • $\begingroup$ You raise a good point on the feasibility on 3D printing at such a time period. The question has been edited to better reflect my line of thinking. Thank you for your feedback, and have a good day. $\endgroup$ Commented Feb 8, 2020 at 23:27

A non-answer that doesn't help you in worldbuilding, but is a realistic evaluation of the usefulness of 3D printers in early-human-history.

How many 3D printed items does the average modern human own? Probably zero, unless he was given one by a friend or owns a printer. If current 3D printers are not used for creating common items now, similar machines probably won't be useful in the bronze age either.

FDM 3D printing is an inefficient process. Compared to casting, cutting, weaving and just about everything else, 3D printing is slow, imprecise, and restricted in material choice. Even if a 3D printer could be built in the bronze age, it would not replace their existing manufacturing methods and probably could not produce items they would be interested in. As a result, even if created, economic pressures would consign the technology to trinket manufacture.

With hand tools, a skilled carpenter can manufacture quite large items in a day. The Amish did barn raising - creating entire buildings in a single day. Have a go with a 3D printing pen and you'll find out that it's a fairly slow process. Modern hobby-grade 3D printers measure extrusion speeds in mm/s (for a 0.4mm strip of plastic). Printing a 10cm cube takes hours, objects larger than 40cm take days. You want a bowl? A guy with a knife can out-manufacture a 3D printer.

Calcium carbonate is kind-of terrible as a construction material. How many every-day items are made out of chalk? How many items that a bronze-age-dude would be interested in could be made out of chalk? Knife? nope, knife handle? nope, bowl? nope?

Even if the material was passable, single material items are limited. A fully metal spear is heavy and unweildy but a fully wooden one can't won't be sharp for long. Even "wonder materials" like carbon fibre and advanced composites aren't used everywhere for exactly the same reason. There really isn't a one-size-fits-all.

So given that 3D printers suck, why do we use them in the modern world (and why do I have one sitting under my desk that I use fairly regularly?)

3D printers overcome their slowness in the modern world because they don't require secondary equipment to produce items. Casting (which was invented in the 1600's) can produce items extremely fast, but you have to make a mold - which can be a much more time consuming process.

3D printers allow data to be transmitted digitally. I can design an item here and send it to you there and you can manufacture it. Transfer of information is cheap and fast in the modern world. In the historical world, transfer of information was expensive and the same speed as sending the actual goods.

Also, many modern items don't need to be robust. I don't manufacture plows, bicycles or knives (aka useful things) on my 3D printer. Nothing that I manufacture would be of interest to Mr Bronze Age.

  • $\begingroup$ you make a fair point at the usefulness of 3D printing. I will gladly take your non-answer into consideration for my worldbuilding project. Thank you for your feedback, and have a good day. $\endgroup$ Commented Feb 15, 2020 at 3:29

Icing on a cake is definitely a form of 3d printing/additive manufacturing...... You could just do what we now do with icing on a cake, assuming the liquid that hardens upon contact with air/water exists (a lot of things in nature does this-- hot plastics for one, but natural resins and cements are among the materials that are available to bronze-age civilizations. (assuming there is enough tin for the "bronze" part of the bronze age civilization, since the majority of civilizations on earth probably transitioned directly from chalcolithic to iron-using due to the exceptional scaricity of tin in the ancient world.))

For the 3d printing to happen, just put the liquid in a sack, cut a opening on one corner of the sack (or add a nozzle to the end of the sack assuming non-plastic-using setting), and squeeze the liquid onto the substrate like how you ice a cake. (submerged into the hardener is the hardening-factor is a liquid) As the material hardens, add more layers until you get to the desired shape. Certain objects, like containers and simple pipes, could be automated using a variety of machinery that involves cams and cam followers. or other sort of bronze-age mechanical computer equivalent of your choosing.


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