Vray Script for randomizing Object IDs and Material IDs
This is a script we use at work. One of the guys modified a script for Mental Ray. It gives random Obj IDs and Mtl IDs to all objects and materials in your scene. Unfortunately as there are a max number of 16 material IDs, that is all you get. Remember to change 'output type' from 'Integer (no AA)' to 'Color (with AA)' to have an anti-aliased pass.
When you run this script you will have no notification or messages, but it will have worked. If you check material IDs and Object IDs you will find they have all changed.