I think it was EricofSD that put up a tut a long time ago for Bryce. The idea was to make a series of spheres that were so transparent that they were barely visable so many units apart coming towards your camera and let the light play off those. I think he incorporated a cone or cylinder as well. You might be able to get something decent this way in Carrara if you play with the shaders enough? cheers, - TJ