An interior cell
with one blue, one red wall
rest is white.
Pickable big white boxes.
http://www.hxa.name/minilight/cornellbox-m.ml1.jpg
http://www.cs.rpi.edu/~cutler/classes/advancedgraphics/S09/hw3_rendering/cornell_box_diffuse_sphere_2.png
Something like this. But walls must be as vibrant as possible.
I'm very excited about this. Thank you.