Skin grafts are the most common method for treating burns, but those take weeks, even months, to heal. Time is critical, because even with proper care, burns are prone to infection. The skin gun, however, only takes 90 minutes for treatment, and only days for healing. It works like this: first, doctors collect skin stem cells from another part of the patient’s body. Then those stem cells are mixed with a water solution and placed in the skin gun. The gun (which is sort of like an airbrush with computer controls) sprays this solution on the burns.