Sculptor inquiry

[ptnorton <ptnorton@suscom-maine.net>]

For the paleosculptors on the list, I'm looking for a non-shrinking, 
self-hardening material that can be used over a wire armature. My project is 
sculpting a replica of a phorusrhacid skull that, as you all know, has a 
number of openings, struts and sheets of relatively thin bone. I have the 
skull modeled in wire and wire mesh, but haven't found the right material 
yet to use to put the "bone" on the wire infrastructure. I'm familiar with 
the common sculpting materials such as self-hardening clays (which shrink 
when drying) and sculpy (which shrinks a little and also needs to be baked). 
I need something that can be worked, but that doesn't need to be baked, 
doesn't shrink when it dries and that dries hard enough to be reworked 
(carved and sanded) and cast once the original is finished.

Thanks. Any suggestions or references to specific materials would be 
appreciated.

PTJN