Best for: Convenience and quality assurance. Technically, this isn't a "download" site, but it is the best free resource. Chaos Cosmos is a browser built directly into V-Ray for Rhino 7 and 8.

Beyond the official library, several community-driven platforms offer high-resolution textures compatible with the V-Ray Poly Haven

Free materials are often "heavy." They use 4K textures that can slow down your Rhino navigation. Here is how to use the best materials without crashing your scene:

: Starting with V-Ray 6, the preset material library has moved to the Chaos Cosmos Browser. This integrated library offers over 20,000 carefully curated, render-ready materials, models, and HDRIs that can be imported directly into Rhino. Poly Haven

If you want, I can:

This write-up explores where to find the best free VRay materials, how to evaluate their quality, and the technical nuances of using them in Rhino 3D.