I'm likely to mainly post about ingredients and formulation, as I'm addictively fascinated, and in some ways it fits with my work (Namikoshi, traditional Japanese that is, shiatsu, mainly for chronic pain) and having to start over and maybe go in new directions.  The good news is, I have tons of time to study before doing much, because of long term illness. 

Which may partially explain my fascination with hair conditioning, since it turns out I don't absorb vitamin B12, and that went misdiagnosed for actual years.  So I'm grateful I don't have bald spots, and know getting well & B12 shots is the first answer, but my poor hair *eek*.  I'll definitely be trying the bhringaraj from the hair oils thread, and need all the help I can get here.

What kind of ingredients add volume - I know anything that adsorbs and forms a hygrophobic film should help, and need help sorting those out.  Think I remember siloxane as maybe doing that (and it's high in affordable Aussie moist!), and silicones generally are great conditioners, but do they do anything for volume too?  Of course a good cationic quat, although those vary too, it looks like rice quat is extra awesome.

Actually I'm not even sure if film forming is the whole idea or what would be.  Also have heard good things about centrimonium bromide, quaternium (number here) and polyquaterniums, for increasing body and volume, but don't know how they work.  Correction, those are cationic quats too, but apparently vary in how much they do for body and volume. 

After that I see claims for forming a film to various degrees, and will give props to making cosmetics for adding info about how much, but all advice in this jungle is super appreciated.  At this point, mega-hold products to fake it can seem necessary.

There are also traditions like crazy for the natural things I mentioned in the other thread being great for hair, but so far the science says great for mature skin (hibiscus) and already in use in skin lighteners (hate that name, wish they'd just call it evening pigmentation or something), which is turmeric.  I'm willing to try a natural ingredient with tons of tradition, without science to back it up so far, but only if the traditional part is real and concrete.     

Sorry about such a broad question, but it would break down into a zillion posts for all of them, so I tried to pick - if many small posts are preferred, let me know  ; )  May try a few of those...