Hey,Biskup
The materials I'm using are Tamiya 2 part epoxy putty that is the resin colour material you see on the head and helmet and part of the front under her clothing.The cloth material is made from Milliput standard also a two part epoxy putty which drys a green grey.Both putty's when dry are hard as rock.
To get the texture you asked about was done by taking a sulpting tool in this case is dental pick and randomly poking at the putty and when its dry sand down the texture to the level you want.The seams where made by adding strips of putty and working them into the piece this was done when it was dry but can be done when putty is wet.
You can smooth these epoxy putty's with water also put a little talcum powder on your finger tips and tools etc. and the putty wont stick to to them.If the talcum is preventing the putty from sticking put a small drop of CA glue (Zap) to tack it down to get it going.Just a tiny drop.
I hope this helps and always willing to share the light.
Thanks XXXNITRO