muesky6969 wrote: Thanks for the information. I like the idea of using the spray foam. But have some concerns, because like you said the stuff that doesn't get hard, is really toxic.
It's not that it's toxic (though all of this stuff is to one degree or another), it's that it is a whole other process that requires mixing parts together, like 2-part epoxys and stuff, and it's way messier, etc. It's going to need more prep to setup, and make more mess and probably more waste. It's the same way they make stuff like sofa cushions and dense automotive padding, the like.
Alternately, you could take actual old sofa cushions of the density and squishiness you prefer, and cut out the shapes you need with a "hot wire foam cutter" (or a thick-bladed (to hold as much heat as possible) butcher knife heated sufficiently to very rapidly cut thru it; I've never found a knife sharp enough to do it without heat and get the shapes and curves desired). I have done this for the cores of some of my snuggle-dolls over the decades, and sometimes the limbs (with wire "bones" in them).
Some cushions are very squishy, and some are quite hard, and evertyhing in between, so you can get whatever you want (and can make layers, as well, to get a particular feel).
When using the cushion material, if you have to make mulitple separate pieces to get the size/shape you're after, you can glue it together with anything flexible that will adhere to the urethane foam without dissolving it; I usually use RTV Silicone, almost always the GE Silicone I caulking tubes like from Lowes/etc. The silicone is much denser than the foam, so if you have to use more than a very thin layer, it's going to make a hard "line" in the core, though you probably cant' feel this thru the TPE unless the TPE is very thin there. (on my cloth dolls I could sometimes feel it thru the surface layers, but not usually).
The biggest issue is for the whatever is in there hold its shape, withstand weight/pressure, also I really want a more realistic feel to their bodies. It kind of a dysphoric feeling when cuddling with my guys and it is just soft with no resistance. If that makes sense.
Yes, it does.
Though personally, I've found I prefer an overall more squishy feeling, though different densities of squishiness are better than the same throughout. I don't really like the "bone" feeling inside, it is kind of creepy, which is one reason I went with heavy-gauge wire with most of my cloth dolls, vs pipes or wood or whatever. The catch is that for anything "realistic" looking, poseable in an easy & natural way, the wire doesn't easily lend itself to that. (and it eventually breaks at any bending points).
As for the abdomen, I may very well go with the spray foam idea. I like that better then just sticking a plastic bottle in there which was my latest idea. For the thigh, calves and butt, that may take a bit more thinking on. I will experiment with the foam, but those are high stress areas and I am worried the foam may not be strong enough to hold it's shape. I will have to look into it and see. Of course if I mixed fiberglass shavings into the foam that may strengthen it enough.. I don't know.
If you use sprayfoam for areas that need to bend/squish, it will not hold it's shape permanently--it is compressible to a degree while rebounding slowly, but enough compression and it's permanent. Anything mixed in won't help with that, unfortunately.
You'd need to use something like the urethane foams, which are the two-part messy-mixing/etc stuff if you do it yourself, or the sofa-cushions if you want the readymade stuff. You can get/make different density mixes if you mix it yourself, or you can find different hardnesses (densities) of sofa cushions, and pick the one(s) that will give you the feel you're after.
The big issue and part of the reason why I want to use hollow inserts is to maximize the weight reduction.
Foam is full of air (which is why it's a foam), and is often more air than material, so it will help with that, if it suits the density/squishiness you're after.
You can make foams of anything, if you have a way to get air (or a gas) into it as it is mixed, and keep it in there until it cures/hardens/etc. Even fiberglass, etc. Some of the foams can be stiffer than the solid material, for the same mass/weight.
Wished I´d find time (and motivation) to apply some on my own doll. Funny thing is... the threads title asks for advice and muesky became the main advisor here now. 
