As we all know, metals exist in nature in compound forms, known as compounds.

Only those extremely inactive metals exist as elements, such as gold, silver, platinum, palladium... These precious metals are stable in nature and rarely react with other substances, therefore they are also known as inert metals.

Hence, most of the metals that humans can obtain in nature exist as mineral compounds, which require smelting to obtain new metal elements.

However, pure metal elements have singular physical properties and often do not meet usage requirements.

For instance, it is widely known that pure iron is actually very soft, and only when it forms an iron-carbon alloy with carbon does it have a hard texture.

Moreover, depending on the temperature, the lattice arrangement within iron crystals varies. Based on this physical property, iron-carbon alloys can be processed at different temperatures to obtain iron-carbon alloys with differing properties, commonly known as steel.

Humanity has a long history of using alloys, dating back over six thousand years to ancient Babylonians, who are known to be the earliest civilization to smelt bronze, which is a copper-tin alloy.

The Flame Country also began using alloys early on; over three thousand years ago during the Shang Dynasty, the ancestors in the Flame Country were already smelting and using bronze on a large scale, and could even produce sharp swords through forging and other processing methods.

The famous King Goujian’s Sword remains incredibly sharp even after thousands of years, capable of slicing through dozens of layers of paper with just a gentle swipe.

Therefore, in human life, alloys are ubiquitous.

However, using 3D printing to print alloys remains exceptionally challenging.

Theoretically, this is feasible, because the definition of an alloy is a solid product with metallic properties formed by mixing, melting, cooling, and solidifying one metal with another or several metals or non-metals.

So theoretically, to 3D print alloys, one just needs to mix the elemental metal raw materials according to the required proportions, then process with lasers to get the required alloy.

However, achieving this is not easy.

Firstly, the mixing of metal powders must ensure the material for each sintering is uniformly proportioned overall, or errors in metal proportions will cause issues in the material’s performance, disrupting the overall structure of the printed product.

Before the disaster, Blue Planet already had laser 3D printing technology; some even printed a set of Iron Man armor from titanium metal, capable of resisting rifle shots.

But this is done within enclosed equipment where metal powders are spread in a layer roughly 0.1 mm or even a few micrometers thick, and lasers are used to sinter the areas to be printed.

Only after repeating such sintering layer by layer can parts be printed.

If airflow disturbance occurs during this process, it will directly blow away the unsinted metal powders.

Slow efficiency and interference from airflow disturbance are minor issues compared to the stringent requirements; such printing is hard to print large parts and cannot print alloys.

If merely processing already alloyed powder particles, then naturally it is simple, but to process elemental metals into alloys is not that easy.

A crucial factor here is temperature.

Sintering is processed at temperatures slightly below the material’s melting point to bond the powder particles, but turning different elemental materials into alloys clearly requires actual melting of materials beyond just sintering.

Moreover, crucially, for some special alloys, processing temperatures need to be much higher than the material’s melting points and must be maintained for some time to allow significant changes in material properties.

These are precisely the aspects that current 3D printing technology struggles to achieve.

However, these are not issues for Chen Xin, who can use lasers to melt elemental metal powder particles, mix various metal elements together to form alloys, then cool and sinter the alloy to become the required parts, which his 3D printer can accomplish.

Chen Xin’s 3D printer is unlike traditional equipment that prints using a fixed framework and print head, instead resembling a small robot.

A small robot carries a portion of raw materials, then melts them into alloys following pre-designed programs, then prints and forms them.

With enough robots, a large part can be printed quickly.

This technology draws inspiration from some sci-fi games where so-called nano robots are often used to manufacture items through 3D printing, which Chen Xin has uniquely adapted.

He just didn’t make the robots so tiny but rather akin to small drone-like robots.

After agreeing to create a small prototype for the engineering technicians, Chen Xin quickly completed the prototype using the workbench and mechanical arms in the shelter and even upgraded it.

"This... this is just astonishing!" The engineering technicians, watching the small 3D printing robot like a drone print a miniature model of the Eiffel Tower right before them, could not help but exclaim, yet appeared somewhat speechless.

"This is the small prototype of the 3D printing equipment I mentioned. It can be made larger or smaller according to different practical usage needs, although this size is quite versatile for various contexts." While demonstrating the prototype of this 3D printing equipment, Chen Xin explained, "It can carry about two kilograms of raw materials each time, which can be pre-processed alloy powders or metal element powder mixtures. Moreover, multiple devices can be networked to print large metal components required."

"With this, architectural construction can become much simpler!" The imagination of engineering technicians began envisioning the sight of hundreds of such 3D printing robots simultaneously starting work, making buildings sprout like bamboo shoots from the ground.

"It’s not just architectural construction; it can also be used in mechanical manufacturing and metal processing. The advantage of using 3D printing lies in sufficient printing precision; printed metal parts may not require further processing, and regardless of how peculiar your needed shape is, 3D printing can realize it." Looking at the excited expression of the engineering technician, Chen Xin smiled and said, "For fields requiring high precision components, this is extremely useful."