Create solid from complex surface

[dambuilder]

I have a surface model composed of 3D faces, from a tin, and would like to add some "depth" to the entire surface. Is there anyway to "extrude" all these surfaces at once in one direction to create a solid? I am trying to model a tunel through a montain and want end up with two solids, one for the "solid" surface and one for the tunnel geometry, and subtract the two. Any other approaches are welcome as well, I am fairly stuck on this one.

Thanks a lot

 

[loeb]

I suspect that you will have to recreate your geometry. I don't know of any way to create a solid from surfaces without using another package to create the Acis Solid to create an SAT that you can bring into ACAD.

Depending on your requirements, you may be able to extrude a section along a path to recreate the "tunnel hole"

 

[dambuilder]

Thanks for the imput, I believe you are right. I am purchasing another program that says it can do this.

Dambuilder