Oh yeah, caustics. To really do those, it needs to be incorporated into the renderer. You've got to trace from the light sources forward, creating lighting maps. And then do a normal render on top of it. Not up to writing one of those yet. Of course with a gel and a well placed spot, they can be faked very well in Carrara. Eric Winemiller Digital Carvers Guild Freeware and commercial 3D extensions http://digitalcarversguild.com

Eric Winemiller
Digital Carvers Guild
Carrara and LightWave plug-ins