Sorry for big pics.
I've been at McMaster University in Hamilton, Ontario, today shooting a piece for Planet Green. While I can't talk about that yet, I can show you these awesome pictures that Dr. Ray LaPierre of the Department of Engineering showed me. (This is the first time they've been online, to my knowledge.)
Dr. LaPierre's group used a focus ion beam microscope (FIB) to shoot a beam of gallium ions at the surface of a human hair, carving atoms off the of the surface of the hair to etch these McMaster University logos. When not tattooing hair, they'll use the FIB microscope to fabricate nanoscale devices.