I will start with the historical making of chainmail. Although they are not quite sure of EXACTLY how they made it, they have a very good idea, and here it is. First of all, you would need the metal from the earth so you would go and get it. The iron would be mixed up with a lot of other different and softer metals that you didn't want so you would have to smelt it first. You would heat up the metal and whack it and all the unwanted metals would spalsh out on to you and scar you horribly (only if you were VERY uncareful, and for those who don't know, I'm joking). After the metal is refined, you then draw it though a hole so that the metal would take on a more wiry shape. After doing this many, many times, and if you were lucky enough that the metal did not break, you could prepare the rings. You would roll the wire onto a mandrel (a rod like thing thats round) as to obtain a round ring which in those times was more ovalish. You would then cold-chisel the spindle of iron into rings. After that was all done, you could then begin knitting your pattern, and you best do it well, lest your Lord punish you. You would close the rings with plyers that you would make yourself and if you were to rivit, you would hammer down the rings. This would make them flat and you would then carefully proceed to punch minuscule holes into the rings. You would line up two holes on the ring and insert a rivit, which you would then hammer shut. Now after reading this, you know why maille cost so much! This process could take months of full work (from dawn to dusk) with apprentices too, for only one shirt. But now the more simpler way....
Today we are fortunate to buy our wire which makes things a little easier. You then take your wire and roll it on a mandrel (sound familiar?) which is most likely a steel rod. You then take the coil of metal and clip off each ring individually. If you need open rings, you must stretch the steel coil first. If you need closed rings, you take the rings from the mandrel and put them on another metal rod and close them individually. Then you must knit all the rings into your pattern. Easier than the medieval armorer, but still time consuming, nonetheless. Most shirts (mine at least) consist of about 6000-10000 rings depending on the size and length, so you can imagine the time it takes to knit it together.