Is there any way to do this ? Basically I have a leather seat that has perforations in it. The leather obviously has thickness but the CAD geo does not. Is there a way to fake a slight thickness with any shader or is this something that could be developed ? Thin surface depth shader or something like that ?
Displacement? 
I was thinking displacement but this is CAD data so not sure how well it would sub divide. I would probably have to retopologise. I was hoping for something at render time other than displace.
Unless you are doing closeups you should be able to get away with just using a alpha mask to knock out the holes. Ive done this numerous times with large oil and gas drilling equipment and with the camera moving or a still shot from a ways back and 99.9% of people viewing will not notice. Otherwise I would either possibly remodel and use displacement or knock out physical holes which can cause huge problems once you get past the first hundred or so. Personally I think a nice clean map will do just fine.
I decided to use a comp map which basically knocks out the holes to black (for diffuse and reflection) and then I used a normal map to give a little bit of light catch around the edges. It gives it more depth…still not exactly what i was looking for but it is the closest I can get bar doing the displacement or geo holes.
I’ve done this before as well, when I had to create a container made of perforated metal sheets. I simply used an opacity map for the perforations and a slightly blurred version of the same map as a bump… that gave some nice edges around the holes.
Still I hope that someday we might get a map to fake thickness on geometry edges (basically like VRayEdgesTex, but viewing-angle-dependent)
Parallax mapping would do the trick… Maby someone can code such material in osl or glsl…