It seems that one of the biggest areas for the application of 3D printers is medicine. They’ve been used in numerous operations and procedures, the latest of which involved the growing of an ear on a man’s arm.

The amazing surgery took place in mainland China late last month and was led by plastic surgeon Dr. Guo Shuzhong. The patient, identified only as Ji, lost an ear but not his hearing in a car accident one year ago.

Last November, Dr. Shuzhong and his team started the first phase of the procedure, which saw doctors implant a 3D-printed skin expander in Ji’s forearm. Water was injected into the expander every day to produce a lump of flesh that could be shaped into the new ear.

The second phase required cartilage be extracted from Ji’s ribs, which was then shaped and buried under the expanded skin, allowing the new ear to grow.

Four months and three operations later, the ear has finally been transplanted onto Ji’s head. The surgery was complicated by the facial injuries Ji suffered in the accident, making it difficult to find blood vessels that the new ear could connect to. The damage is why conventional artificial ears won't work for him.

“The whole operation had to be done using 10x magnifying surgical glasses and sutures thinner than human hair,” said Dr. Shuzhong.

Despite the difficulties, Ji has now been placed under observation and is scheduled to leave the hospital in two weeks, by which time his new ear should be working normally.

3D printers are becoming increasingly common within the medical field. The FDA approved the first drug made by one of the machines back in 2015, and a number of implant operations have been performed using 3D-printed body parts, such as jaws and sternums and ribs.