My idea would work so good, it's just really hard to explain and I have no way of doing it. First, you would start out by building an area using 64x64. Then when you want to dig, there would be two diggers. One would be for fast digging (Removes 4x4x4 chunks) and the other would be for accuracy (Removes 1x1x1). When you go to remove a chunk, the big brick would split into the largest avalible bricks covering everything but that spot you shot. Sorry if this is confusing, I'll try to draw a picture.