One of the fun things about writing science fiction is that I don't have to be exact, but I still get to play with numbers. While working out the plate model for how the Iliad would be built, I had to contemplate what materials such a ship would be made of, and where those materials would come from.

Our asteroid belt has a lot of materials for use to work from. Some of it in the form of dust, clay, and otherwise mixed up minerals. Some of it in atomically pure metal. Those pure metals have another interesting property: a crystal structure we could only dream of achieving on Earth.

Just about every metal you and I interact with has been melted down at some point during the manufacturing process. Solid metal actually has a crystal structure. Imagine a crystal in your head. and you are probably thinking of Quartz. If you analyze quartz chemically, it's mainly SiO2 (Silicon Dioxide). So is glass. The The difference between glass and quartz is how long the material was allowed to cool. For glass, the cooling time is a few hours, and the crystals structure is non-existent. (Glass is considered an amorphous solid.) For large quartz crystals, the cooling time is on the order of millions of years.

For many applications of metal, the material is heat treated. That heat treatment is maintained at a specific temperature for a specific amount of time to promote the formation of a specific crystal structure. Aircraft aluminum, for instance, is virtually useless as a structural material until it has been heat treated. The reason airplanes are riveted together instead of welded is because a weld would erase the heat treatment in the material.

Getting back to the asteroid belt, one really interesting body is an asteroid called 16 Psyche. That little world may be the remnant of a planet's core. It is thought to be mainly Iron/Nickel metal. While Iron/Nickel alloy is already a good choice for a steel structure, the main engineering interest may be in that the Iron/Nickel had millions of years to cool before solidifying.

I am putting on my Science Fiction author hat here. Nobody has actually sent a probe to 16 Psyche yet (though Nasa has a mission on the drawing board.) But what if we discover some exotic and strong material that is unlike anything we would find on Earth? Rather than melt down the asteroid, you would take strips or blocks of the material. Like quarrying marble from a rock face. An extremely large crystal material would probably be tough, though somewhat inflexible.

Given that it is a Natural material, with defects and an uncertain ultimate breaking strength, you wouldn't trust it for structural members (like trusses, or I-beams.) But for plate material it would be perfect. And if a plate fails, or cracks, you can either replace it or simply weld the rend. All of the shavings from the quarrying process, and rejected plates, could be melted down to make conventional mild steel, or if you don't feel like pulling the nickel out, the material is already close to the right mixture to form Maraging Steel. (Though Maraging Steel requires a bit of heat treatment.)

The hybrid of industrially processed material for structural beams, combined with cheap, cheerful, and extremely strong plates is a match made in the heavens. The other cool thing is that any plate on board can be sanded and clear-coated to provide some breathtaking scenery (Pictures courtesy of the Smithsonian Natural History Museum:

To preserve the integrity of the plates, they would most likely be riveted, bolted, or simply pinned to the maraging steel frame. The less interesting (visually) plates would likely make up the floor. The more interesting plates would be wall features. Most of the material is going to end up covered in insulation, soil, or paint. But every once in a while our character is going to encounter this exotic material where it sticks out.

Each of the plates will likely go through some sort of minimal integrity testing (having a machine bend it slightly, or hit it with a hammer) so every plate will have some sort of proof marking etched in a corner somewhere. Many will be cut to either one of a standard set of sizes, or a shape for a specific location on the ship. They will also have some sort of etched marking indicating that information as well. For inventory tracking purposes, every plate will also have a Universally unique identifier.