That physics bug I was dealing with was an easy fix. I had moved the center of gravity of my little robot a little to low to prevent him from toppling over, and in the cases where he was pressed against a sharp corner he could actually snap through the walls and floor. Looking at adding different building modes for my robot, so that you are explicitly moving, adding or subtracting pieces from assembled blocks.
I also took a few hours to get my hands wet with making shaders and image effects for Unity so that I could easily create some interesting effects.
Used an outline shader along with a separate camera and duplicated objects to create this sort of Left 4 Dead highlight effect that also will be visible when the objects fall behind others.
I am now making it possible for my little bot to disassemble the block he has already assembled in case he makes mistakes.
But hey, work continues.