Hi Elrick, the "metallic lighting" option will tend to make curvature more apparant, it basically makes the lighting work in a reflective style.

re: Shelling - unfortunately the geometry library that MoI uses does not have a particularly robust shelling mechanism and so shelling can have problems in many situations. It will be particularly difficult to shell or offset surfaces that have tightly bent areas in them where you try to use a thickness that is greater than the radius of curvature in those areas. That will cause the offset result to have badly formed surfaces with self intersections in them.

The geometry library in other CAD programs can tend to do a much better job of shelling than MoI, you might try exporting your model to ViaCAD which is inexpensive (like $99) and see if it can help you out with some of the more problematic shells.

- Michael