Iron Man
Until now I used:
Cardboard - You know what is this
Cardstock
The brown card that is on the end of the technical block
Then the brown paper i cut into small rectangles
Next, I glue them into this think. This is very hard. I put this brown paper into inside of armor. Now armor is stiffen.
Next, I make a Paper-Mache outside of the armor. I will sand Paper-Mache layer and paint it.
TankBoy
Whan you made Paper-Mache layer and you sand it, it will be smooth.
Preparing for paint? Hmm... I have a normal spray (Sweet Red and Sun Gold), First i sand a paper-mache, next I spray a hardening lacquer, whan it dry, i will pant this on Mark III colours.
PS. I dont use body fillers because in my country this product is very expensive, and sorry for my english what is not so good