You know how when you're using a hot glue gun, and you get all those little strands of glue forming when you pull the gun back from the surface being glued? Well, researchers at Carnegie Mellon University have used that same principle to create 3D-printed "hair." The discovery could allow for the creation of 3D-printed devices containing brushes or bristles … or even for making troll dolls.

Led by PhD student Gierad Laput, the team used a US$300 off-the-shelf fused deposition modelling 3D printer – this means that it creates objects by laying down successive layers of molten material. In this case, that material was polylactide (PLA), a commonly-used printing medium.

To make each hair, the printer's nozzle first deposited a small glob of molten PLA on a base (such as the head of a troll doll) mounted on a print bed. The nozzle and the print bed were then quickly drawn apart from each other horizontally, causing the plastic to stretch into a filament between them. That process was repeated over and over, with the nozzle depositing each new glob in a tightly-spaced grid pattern.

It isn't necessarily a fast process – yet – with it taking 20 to 25 minutes to deposit hair on an area measuring 10 square millimetres. It also doesn't require any extra hardware, however. All that's needed is some reprogramming of an existing printer.

The nature of the hair is determined by how it's applied. Random placing of the filaments results in a more natural-looking finished product (i.e: the troll), while more precise placement can be used to make things such as toothbrush bristles. Additionally, if materials such as ABS were used, it could be possible to create hair with properties such as magnetism.

You can see the process in action, in the following video.

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