Looking for a flexible, semi-rigid foam for 2-1B positives.

[forttusken]

I need some foam that can be carved but bent to form the base, over which I will put a layer of clay for texturnig to do the upper an lower torso parts. I bought some white foam for model railroad scenery but it just cracks even though it is supposed to be flexible. I need to be able to make about a 3" radius. Preferably something 1/4-1/2" thick or so I could layer so it stays bent. I know I could do this out of a solid block but trying to carve out the inside so it fits right wouldn't be too easy so that is a last resort.

Thanks in advance.

 

[forttusken]

Any other ideas? I am about ready to just do this with cardboard base, plaster and clay over that.