Hey Crazy Diamond... shine on!!
I was terrified of all this stuff at first; I didn't even learn to do the dry-burning stuff until I was down to ONE working coil and knew the replacements wouldn't be here for a couple days, so I kinda had to learn it. It's easier than it would seem; when I heard "dry burning", horrors, I couldn't even imagine doing something like that, but it's not difficult at all (just getting the coil disassembled was a real challenge for me, the first time I did it!), and it really extends the useful life of a coil.
I was even more terrified of this rebuilding idea, but gosh, everyone here blathers on about it so incessantly, my curiosity finally got the best of me, I started accumulating all the various bits I'd need to get it done... then had to RE-buy wire, since 30ga seems to be for those who want very low-resistance coils. If you want a "normal" coil, like 2.5 ohms or so, you really need 32ga kanthal. Then I bought some 1.5mm silica, the regular "braided" kind (it's really just twisted, but they call it braided for some reason), and it's ok for flavor wicks, but really too small for the coil wick, and too fat to double in a 5/64-wrapped coil; actually I haven't tried doubling it in a 7/64-wrapped coil, but that might actually work.
But what seems to have solved it for me was getting this hollow braided "ekowool", which is a trademarked name for this particular type of silica. I got 2mm, and it seems to work really well in the 7/64-wrapped coils. It can be a real challenge to thread into the smaller 5/64-wrapped coil, so I'm sticking mainly to the 7/64 drill bit these days.
The thing I read that seemed to shine a light on what's going on, what's needed, for these coils to work well, is that there needs to be air spaces for the juice to occupy. Apparently cotton works well for some, in some types of atomizers; cotton's absorbency is well known, so it does seem like it would be a useful material. But with these tiny T3S/protank heads, the coil and wick are enclosed in a tiny space, and that concentrates heat, so much so that cotton just doesn't do well in these types of coil heads -- as Picowatt noted, you get a lot of burning in an amazingly short time, at an amazingly low heat, and once that cotton is burned *at all* it has to be replaced or the rest of the tank will taste like that, that bitter burnt scorched taste, ugh.
Some people have some sort of mental problem with silica, imagining all sorts of horrors like inhaling silica particles, etc, but I would have to say that it seems most unlikely to me. I mean sure, if you took that silica wick and ground it up and tried to snort it, that would definitely not be healthful, but for its intended use as a wick, I really don't see any problem. Silica stands up to high heat MUCH better than cotton, without giving that scorched taste. It's always possible to get a dry hit, if you have too much wick, and then you'll taste that burnt taste no matter what your wick is made of, but when the wicking is the minimum necessary to keep it from leaking, silica works GREAT -- and one thing I've noticed is that although it's possible to get a dry hit, that one dry hit doesn't ruin the whole wick, if it's silica. If you take a priming puff or two, really get the wick saturated, the burnt taste will vanish, even if you've had a dry hit from that coil already. Of course if you take too many priming hits, you'll flood the head, and then you'll have gurgling and leaking.
The hardest part of building these coils is finding the proper amount of wick, to prevent both leaking and dry hits -- and it will vary from juice to juice; the thick ones will tend to the dry hit problem more, because it takes longer for the wick to soak it up, but the thicker juices don't seem to cause the leaking problems so much. The thinner juices will just run right thru the head if there isn't enough wick to absorb it, and that can also cause that nasty "gurgling" when the head is flooded, under the coil. But if you use too much, trying to stop the leaking, then you run into the dry hit problem once again. It's a very fine balance indeed.
Hope that will help you shine on, you crazy diamond.

But I still buy replacement coils too -- just on the chance that I won't have any good ones ready to use, I can always grab a 'store bought' and vape away.
Andria