Hi Michael and Brian,

It is all created in MoI and I would assume that the order would depend
on the object creation list in the browser, like starting from the first object
in the browser until the last. Then I gues it would only need to define a starting
color and a second end color, which then computes the steps between.
To have a rainbow one starts with red values on the left and the second color
would be the red on the right. Maybe you have a better idea.

I had such a script years ago for Shade3D and it worked in the same way.

@Thanks Brian! Do you have a link for Karsten's node handy?

Best regards
Stefan