I try to render an image of a model made of optical fibre. I create it by extruding a cirle along a path. When I apply a glass material I get a very dark render image. I think this is caused by intersecting geometry.
After converting the curve object to a mesh object, I have tried to apply a boolean modifier (Operation: Intersect, Solver: Carve) with a cube. Unfortunately this operation results in an error message ("Cannot execute boolean operation").