" then one day it was the full box."
It seems as it the problem is with the implementation of this concept. The box is supposed to be a 3d representation of the block you plan to dig out. At the proper angle, the blue box matches up with the tile; however, under all but one angle, the blue box doesn't get angled in a manner that maintains spacial relation with the tiles. As if the blue box doesn't change as POV changes.