Testing automatic inclusion of GH geometry with custom materials in the render process. This can be done using the [Custom Display] component in next weeks Serengeti WIP release:
Be careful when baking though, all too easy to end up with something like this:
nice!
Here are four ways to assign materials to the custom preview.
Fantastic! This is what I’ve been waiting for 
@DavidRutten @nathanletwory Will it work with new shader components?
Ah, that brings up an old wish: The ability to purge similar materials and also to drag a material on top of another to both merge those materials and their assignments. Those are very handy tricks to tidy up a file.
PS! Looks smashing!
-Jørgen
The Material type in Grasshopper should also be able to handle Xml material strings, but I haven’t tested it.
For that you’d add a Cycles XML Material which you the reference like a normal material added to a Rhino document.