Tens of millions of people each year find themselves in need of replacement body parts, but face a shortage in donor supplies. Many tissue engineering approaches (i.e., growing replacement body parts) have made great progress but still are limited in the complexity of the shapes that can be grown. My work was some of the early attempts to 3D print living tissue. The idea was to 3D print a hydrogel filled with a patient’s own cells in complex shapes directly from CT/MRI images. I modified a hydrogel material that had been used in other tissue engineering techniques so that it would be compatible with 3D printing.