I took this seriously, but had fun with it too.  The walking-Christmas-tree-light guys are arguing over the best place to hang the picture of the last time they argued over the best place to hang the picture, ad infinitum.

I swapped the IBL image for another, but left the sky alone otherwise.  Each of the metal balls has a point source inside, set to not cast shadows, with low intensity and ranged falloff.  The glass ball has a spot, squished along Y, shining straight down.  That light uses the rainbow volume mat as a gel, and the lights in the metal balls use gels made from their respective mats.

Since we could change mats I cheated and applied the steel cage mat to the ceiling.  This actually made the most dramatic difference in ligting.  In the end, I only added a bump and some specularity to the walls, which were default gray.  The floor mat is an adaptation of one of my engine-turned mats in the free stuff.  The octopus-looking thing wears a neat volume mat I downloaded years ago.  The cosmic coatrack has one of Tony Lynch's wood mats, the grain going the wrong way as is the alien custom (They get very little service out of a baseball bat).

The lights inside the spheres is a way to fake radiosity.  It is not done to the best effect here, but test renders were taking a lot of time.  I think you get the idea.

Fun challage, MatCreator.  Thanks!

John