Adding difference option to the construction system

Its hard to describe but imagine using blocks to produce a hollow square which will be your wall and where your window will go. You use planks and the grid system to put panels on the wall, covering the open space for the window. you move around to the other side of the wall that you havent covered yet and place the window frame such that it cuts through the planks covering the other side (and with the difference modifer on ie: holding control+alt) when you place, allows the window frame to cut a hole through the plank. With a difference option (the ability of one object to cut through and alter another objects model) the possibilities of what can be created are essentially endless. At that point, so long as we have primitives we can model whatever we cant already find prebuilt in the game.