I don't see what you mean, don't you just do that with z_elevation.
I don't see anything different, unless you mean shadows specifically....in which case why not say "shadows" instead of "depth"
I'm not talking about shadows, its the actual placement of the boxes?
Picture1 is a screenshot of this cap:
I want the cap to end up like picture 2 (doesn't have to be random) with the boxes spread about, and the ball in the middle?