With the help of 3D printers medical staff has the ability to better prepare for the planned operation by analyzing possible scenarios on physical models of any part of the human anatomy. Solids can be printed  from a CT or MRI file. With 3D printing technology one can also create dentures and implants perfectly matched to the user. You can create a cheap but at the same time very complex structures, such as spheres filled with constant inside and outside of the porous surface to the nearest mm.