Surgeons were once forced to plan their work on the complex structures of the skull and facial areas of the human body with nothing but two-dimensional data to go on. The results of CT scans, while very useful, lacked a level of detail critical to a full understanding of the anatomical problems involved. Now a group of Russian researchers, among many others, have created three-dimensional models to guide doctors as they perform their work on the delicate architecture of the human skull. You can read more about how additive manufacturing and 3D printing are being brought to bear on surgical techniques and problems here: http://3dprint.com/32191/3d-printing-for-skull-surgery/ ‎