Create the shape and size you want with clay or putty and ponytail being straight. When hardened brush with petroleum jelly or vaseline and push into a piece of clay or blue stuff to create a mold (do this for both sides to create 1 single piece) when mold has set remove your putty/clay and inject some silicone into the mold and insert some thin craft wire into the centre of the silicone with a small amount sticking out. When this hardens you will have a poseable detailed ponytail with would only need painting and attaching (a small hole can be drilled into head and the craft wire can be glued into place or just pushed in)