It is a composite of 2 computer generated (CG) images of rendered 3d models which took approx. 4-6 hours render time each, not counting the time to create the models or set up the scene (2-3 weeks). It was finished off with some minor postwork in PhotoPaint. The larger image posted here has been greatly reduced from the original in both resolution and dpi, that is, it is not print quality like the original.
