Ok, thanks Frank. What about the resolution? I've seen Calculus books that use Mathematica graphics almost every other page, and they look very clear. How do they do this?

Are you exporting a 3D graphic to eps?

A mobius band might very well have many many many polygons in it or very few. So maybe a raster would be actually more faithful to the image in the end than a vector graphic.

When you export something 3D to a vector graphic, it'll export the entire thing into the vector graphic, not just the parts which are visible. So if you have a complicated 3D scene to render, but most of it isn't visible, you will want to cut that part out before exporting the result to a vector graphic. The exporter doesn't "flatten" out your 3D graphic by doing some kind of ray tracing. That probably would introduce too many possible issues.