Using noise to get different roughness on each cube

Ducky said that he hadn't found a way to get the roughness noise to be used over the entire node system. I Think I have a way to accomplish that. At least it worked in this animation.

This is what I did:

• UV unwrap the particle, and align the voronoi using "UV coordinates".
• Add a "realize instances" node at the end of the node tree.
• Use "object coordinates" for the noise texture driving the roughness.

This gave me a flawless loop, with a noise pattern that covers the entire grid for more variety.

This is how my material looks: 


I use an empty to control the heat gradient. But that is just because I like to adjust it from outside the material.