Well, for all I know RDS formulas could be very different. If you really want to mess with formulas (and I've only scratched the surface) I'd start with something simple like plain ol' stripes, first. You can do this with a one line formula in Carrara: red=z-floor(z); (z is the vertical position, floor(z) is the next lowest integer, or at least that's what it is in Carrara).