They printed a skull and stuck it in someone’s head.

Singularity Hub reports on the pioneering surgery that used 3D printing to replace 75 percent of a patient’s skull:

At the beginning of March of this year, a radical surgery was performed on an American patient: 75 percent of his skull was replaced with a 3D printed implant. The company that produced the implant, Oxford Performance Materials, made the announcement though offered little detail about the patient or the procedure. The surgery was given the green light by the Food and Drug Administration in February.

The implant is called the OsteoFab Patient Specific Cranial Device (OPSCD) or OsteoFab for short and is made from polyetherketoneketone (PEKK) thermoplastic through an additive manufacturing process. This material is not only biocompatible but is bone-like and will not interfere with x-ray scanning. After the patient’s skull was 3D scanned, the custom-made implant was printed using an EOS P800 laser sintering 3D printer. By generating the implant layer by layer, details can be added that promote the attachment of bone and surrounding cell growth.

Turnaround time for receiving an implant after submission of scans is two weeks or less.