Daniel Mozbäuchel (iDani) shares a really useful script he created for C4D. The easy to use tool is a python and Expresso driven script for C4D that will allow you to easily add weathered and worn edges to the edges of your model.
The Worn Edges script will invert the model’s normals and set a TextureBake Tag for it. Then the script will bake the AO Channel in to a VertexMap and invert the Normals back. The Expresso rig can then be used to control the look and setting for the worn edges.
The Worn Edges Script for C4D can Downloaded from Daniel Mozbäuchel’s site, 4dm-works.com under the Goodies section- Be sure to check it out.