High density foam for crafting, available in 5mm and 10mm thicknesses.
Cosfoam is a heat-mouldable foam suitable for making armour and props.
Because of its high density and closed structure, the surface is very smooth. It requires only minimal priming before painting. If you heat seal the surface then you may not even need to prime it first, depending on the finish you're after.
When heated, the foam will have slight shrinkage. This is unnoticeable when moulding, but becomes useful when you want to create carved details. By scoring the foam and then heating it, the cut "opens up" and becomes obvious.