I’ve been thinking about what to write next in regards to this build, and realized I could write a novel already. And I’m not even finished with the legs!
First things first - I have reason to believe that a key aspect of the build process is directly tied to a piece of trivia regarding the Gundam Mk. II. So as not to bog down the build discussion with such a matter, I’d like to cover it in this intermission. If you’re an engineer of some sort, or you simply don’t care about the internal workings of fictional robots, you will be OK if you skip this post.
During the One Year War, mobile suits were built using a monocoque or semi-monocoque design. Each part of the suit - the torso, forearms, ankles, etc. - acts as a kind of shell, which provides both protection and structural support to all the gears, motors and fuel tanks underneath. Near as I can tell, this means that if you were to look at the leg of a Zaku, everything on the inside would be bolted onto its green armor plating. If you were to somehow strip away all the plating, the leg would just fall apart.
The Mk. II, on the other hand, was one of the first suits to move away entirely from the monocoque approach, by using an internal frame (called a Moveable Frame) for support, much like a modern aircraft or automobile. The frame itself could technically move and function on its own, and armor could simply be attached and removed as needed.
Apparently there is an in-universe explanation for this change in design, which goes something like this: Engineers began to realize that the weapons wielded by mobile suits were so powerful that the suits themselves rarely withstood more than a single hit from one of them, regardless of how well armored they were. The only way to survive was to evade, and so speed became more and more important. That meant shedding weight, specifically armor plating. A suit built with a Moveable Frame could have armor attached at only the most sensitive and critical areas, while other parts went “bare”, so to speak. The result was a craft which was lighter, faster, and on paper more fragile (but in practice, an older mobile suit with more armor wasn’t really going to withstand a hit from a beam rifle any better).
Unfortunately, I haven’t found many sources which explain the Moveable Frame’s ultimate fate. It was used by other mobile suits from the Mk. II’s era, but I found some claims that it was abandoned after the Neo-Zeon war, possibly due to its greater cost and higher maintenance. Of course, this is also why the numerous transformable MS designs introduced in Zeta Gundam all but vanished in later conflicts: they each cost a mint, and the transformation mechanisms were unreliable. In other words, the theme of Zeta era mobile suit design could be summed up as “a bunch of failed experiments”. And people wonder why I say it isn’t my favorite UC show.