Show wall thickness on Opacity Maps?

[tomlehn]

Is there a way to have opacity maps show the thickness of material? I have attached an image for reference.
Any help is appreciated.
Tom

[Will Gibbons]

You need to model such a thing. The only other option is to stack a bump with the same mesh (slightly larger) with a soft edge to create the illusion of 'depth', but it's still not going to fill in the space between your two surfaces.

[tomlehn]

Ok thanks Will. At least I'm not chasing a wild goose :-)