Observation #1: Sometimes when you pull a glue gun back from the item being glued it leaves a thin, hair-like strand of hardened plastic.
Observation #2: Bald guys have no hair.
Although assaulting a bald head with a glue gun seems a bit unrefined, there is another way. Researchers at Carnegie Mellon University have used a simple, off-the-shelf 3D Fused Deposition Printer to produce polylactide hair. Like any good machine, the device can repeat the process over and over in a compact grid. Programming a random pattern can create a more natural look, and the color choices a nearly unlimited.
One small drawback is that it takes almost a minute per hair, and the average human head has around 100,000 of them. You don’t have to do the math to grasp just how badly you would have to want hair to spend this much time under an automated glue gun.