A particular weave of chainmail that is a denser form of European four-in-one. In six-in-one, each link goes through six others, excepting edges and corners. Six-in-one is a nice all-purpose weave, thick enough to serve as armor even with the lighter gauges and larger link ID's.

Like four-in-one, six-in-one is usually hung in shirts so that the rows run horizontally, and the maille expands when you breathe. Strips of it that are at least three rings wide can be used as chains for necklaces, bracelets, guitar straps, sword frogs, etc.

Six-in-one sometimes does the funky dance, and looks like part of the weave is trying to slide sideways sans the other part. It can be kind of disconcerting until you've seen it a couple of times.

Tables of gauges and ID's:
You should be able to extrapolate more information from these tables.

12 gauge

• Haven't tried it yet

14 gauge

• 1/2" ID: about as normal as you can get with these huge links and such a thick weave
• 7/16" ID: heavy
• 3/8" ID: unpredictable, but close to insane or impossible

16 gauge

• 3/8" ID: normal
• 5/16" ID: heavy
• 1/4" ID: can only be done in 3-ring wide chains, and even then it's stiff

18 gauge

• 5/16" ID: normal
• 1/4" ID: heavy
• 3/16" ID: wow, that's going to take too damn long

Smaller gauges are really only useful for jewelry. I have yet to try six-in-one in 1/8" ID rings. Tweezer mail!

I will attempt to write instructions on how to weave this stuff. First, make one chain of 3-in-1 (ie, three links in one in three in one...), with the ends being three links, and nine (this number really doesn't matter) single links in each chain. Place this chain horizontally in front of you; position the links in each chain so that the single links are going up and away from you, and the triples are going up and towards you.
Now, close a handful of rings. Then grab another ring. Open it right-hand-back (the right side of the ring goes away from you if the opening is at the top). Grab it roughly in the middle with the tips of your pliars (pliars held perpindicular to your vertical axis, so the plane of the ring is parallel to your vertical axis), and then rotate the link along its current vertical axis in the pliars so that its opening faces away from you. If this doesn't make any sense; don't worry, if you try it a couple of times you will figure it out.
On the left end of the chain, on the bottom, you are going to add this ring that's in your pliars right below the first single ring. But before you add it - string two closed rings on it. Now, put the ring's left end up through the bottom two of the far left triad. Put the ring's right end up through the bottom two of the next triad over, and close the sucker. You have begun the pattern.
Move to your right, and add another single to the pattern; this time, though, you already have three rings on the left to hook it through (the bottom one is one of the closed rings you added in the previous step), so you only need to put one closed ring on this one before you add it (hook through three rings on the left, two on the right). Repeat until you have a huge-o piece that you can sell for a sum of money that will, in all probability, not reimburse you minimum wage.

That's the best I can do. I suggest looking online for visual aids.

Related weaves:
European four-in-one
European eight-in-one
Boxchain

This weave was never widely used historically, due to its extreme weight (Approximately 1.5 to 2 times a similar garment of European four-in-one mail) and only slightly improved protection. One possible historical example does exist, a fragment of a bronze Celtic hauberk which has corroded into a solid mass. Because of its condition, it is difficult to say definitively that the shirt was made using this weave.