I know we have a section for modding materials, but finding materials for making parts is a lot harder.
First of all, there is a wonderful tutorial in the pinky uni on making molds. This is for materials to put in the molds, and small part molding.
I don't currently have pictures, my camera is out of commission, but once it's fixed I'll update this with pictures of the different materials and good methods for casting.
MATERIALS:
I'm mostly going to start with the ones I use... If anyone else knows good onces mention them please to they can be added?
1. Smooth-On(Smooth-Cast)
a. 325 versus 320
b. Color Tints
2. Feroca
a. Mold Making
b. Casting Materials
3.Oyumaru
4. Epoxy Putty
5. Plasticine
Smooth-OnThe one I've mostly messed with is Smooth-on 325. It feels quite a bit like a pinky after hardening, and has the same malleability. It bends nicely like one, and has a similar weight. The problem is it comes in a clear color of an opque color, so you have to apply a large quantity of paint to it to cover that up.
The 320 line is more rigid and stiff, not feeling quite so pinky like I've found, personally I'd recommend the 325 for liquid castings.
Colors. Smooth-on fixed the clear color problem by selling colors to add to the liquid before you mix them, a wonderful idea, yes? Except they only have five colors and they're 20 dollars each. The instructions are also rather vague. I haven't worked with it, because I decided my dollar paints worked fine.

Okay, finally tried the colors from Smooth-On. They don't fix the transparency at all, and they're incredibly strong colors. But even after using the colors you can still see through the pinky part you just made. =/
FerocaI haven't personally worked with it, so I don't know how good it it, but it's Spanish(Portugese?) So probably easier to get in Europe than Smooth-On(Maybe?) They have both materials for making molds and for the castings, and the casting material hardens to an opaque color.
*_Raurenu_* provided a link to a tutorial using Feroca
here.
OyumaruOyumaru is NOT for the actual parts you want to make. It can be used for small part molds however, since it is easier than the method shown in the pinky-uni for things such as hair or accessories.
You simply heat up the Oyumaru in a pot of almost boiling water for a few minutes, take it out and it's shape-able until it cools. It's also reusable, and neither Smooth-On nor Epoxy stick to it(even if you don't use some sort of lubrication). Once it hardenss you take out the piece you molded it around and you're free to pour another material or smush epoxy into it.
Epoxy PuttyWhile epoxy putty works great for modding and little things like bags, if you make a mold for hair do NOT make your hair out of epoxy. It makes your pinky incredibly top heavy, and it's also fairly difficult to get it into the peg holes on the bangs. A better method is to use a pourable resin to fill up your hair molds.
PlasticineIt's used in a couple mold making tutorials because it doesn't harm pinkies nor take off paint or anything. Pretty much it's a fancier term for play-doh. Non toxic, works great for making molds, just make sure you clear it all out before you try to cast using the mold.
And that's all I have for the moment. Will add more once I has a camera/more info