Do you use the Vray Material Override to do chalk renders and wish that it would allow you to exclude certain materials? Like VRayLightMtl and any refractive materials like glass?
Well now you can using this little script. It sets up a Shell Material which allows you to switch from one material setup to another. So even if those pesky VRayLightMtls and refractive materials are within Multi-sub materials then you’ll still be able to exclude them.