Thanks.
It's not just a matter of the thickness. Modern flat rings, punched or riveted usually have almost 90* corners as they transition from the face of the ring to the edges of the ring. The edges themselves are also usually perfectly flat. A lot of historical flattened mail, because it was originally a round ring, the edges retain their roundness, and the corners are also very rounded. Historical solid ring mail varies though, because some of the metallurgical and grain analysis seem to suggest that some was literally punched, and some were welded closed. If a ring is punched from a sheet, the grain of the steel should all run parallel, if it was a welded ring then the grain follows the circle of the ring as it was bent around a mandrel. There are examples of both in historical mail, so it's not really universal.
All my mail is 9mm, but again, historical mail varies a lot in ring size. I don't really have a preference. I don't think that 6mm is universally more accurate than 9mm or 8mm or anything like that. In historical examples there's even variance within the same garment of ring size sometimes.
When you say fauld are you meaning the mail fauld? I would probably just use a thin piece of deerskin, whip the fauld to the bottom edge of the deer, and strap the leather like a belt, 3 or 4 inches wide. If I was using my leather lendenier, I might even just whip the mail directly to the bottom edge of that. I've never worn mail skirts, so I don't have any practical experience with them. Those methods would probably be my first go at it though.
That mail shirt is just an oiled finish. It's usually slathered in firearm solvent/oil too. I hate handling my mail...
My new helmet's aventail has darker mail. I don't know of any evidence for actual blackened mail in Europe. Most of the artwork is explained as tarnished silver leaf. Some seems like it was intentional. Mail really isn't my thing though. It's really a subject that requires its own study entirely separate from plate armor, and it's something I admittedly haven't studied enough. Whether mail was ever blackened in Europe or not is still fiercely debated.