The title is a bit complicated (If you have a better one just tell me 🙂 ), but this is super simple in Maya with Arnold 5.

While using MASH with the Instancer geometry type you don’t have access to MASH’s Color node, but you do want to randomize the colors (and other attributes) of the instanced objects.
There is a simple way to do that:

1. Create an aiColorJitter node.
2. Select a color at Input (or connect a texture)
3. Use the Object randomization part to create different colors/values per object
4. Connect aiColorJitter node to the shader
5. Change the Seed value to get different randomization

Done. 🙂

You can also use this node to randomize any User Data, Procedural or Face driven input.
Unfortunately there is no built in clamp feature in this node. So you may have to connect a Clamp node after this.

Cheers, D