rendering 3-d query

When using the 3d extrude and bevel tool set to 'plastic shading', the 'side' created by a curved shape shows parallel construction lines similar to a wireframe. I want to incorporate these as part of the design but when I click 'expand appearance' these are unaffected. Is there a way that I can render these as a feature of the vector image? (I have tried rasterising and re-tracing but this causes an unacceptable loss of detail).