Just a test with:
- a principal path rotating at 360 °,
- a second path rotating around the first path.
Here is an example and the .blend file, with explanations inside the blend file.
Edit 20H13: just changed the image with less light, and parameters changes.
Edit 2013-12-02: changed the image again with less light, 200 000 frames, and corrected in the graph editor the interpolation of the X euler rotation (linear instead of Bezier)
Path.blend.zip (85.9 KB)