How to clip a material and give the illusion that it is 'solid' or 'filled' with Cycles? I am using a combination of Cycles material shaders to perform a "clipping" view for a geologic cross-section. The answers to the following question  explain very well how to achieve the cut-away view. 

How can I easily animate cutaway views on multiple objects?

The difference between these answers and what I am looking for is that with these you can look inside the mesh. I would like to give the illusion of a solid or filled mesh. Even if it appears to be filled with something like colored smoke. 

I'm trying to cut hundreds of objects, and cut multiple X-sections (e.g. clip the Y-axis from 90-110, and 190-210, 290-310, etc). 

This is an example of an original mesh that I would like to clip:


This is what I would like to accomplish. I did this using boolean modifiers. The problem with this method is it does not scale well to many objects, nor is it simple to make multiple X-sections.


This is where I currently am using Cycles nodes. 


This is the node tree with two groups:




I believe that a volume or emission node may be able to provide this effect. I have tried adding it in a variety of places. 

Placing the volume absorption node right before the material output:




Placing the volume absorption node between the diffuse node the first location group results in this:



Is it possible to have this geographically clipped material appear to be solid or filled with smoke?
One option is to do it manually.

1) Press TAB to go into edit mode.

2) Select all the vertices bordering the hole.



3) Press 'F' to fill the selected area.



I hope this helps! -Galaxy