Practicing for an operation

And it's a serious operation - on a young girl's brain. That's what the doctors at Children's Hospital do - practice for an operation. What do they practice on? an organ, such as a brain, printed with a 3-D printer. 

They have built over 170 models over the past 18 months; in addition to brains they have built skulls, spines, rib cages, and blood vessels. The hospital is using the printers to avoid surgical complications, reduce the length of operations, and ultimately cut costs.

Here's a model of a brain: