Answer: Hair

Anyone with curly hair will tell you, curly hair is wild, full of life, and unpredictable in its movement when compared to the simple order of naturally straight hair. Given that just styling and managing curly hair in real life takes quite a bit of effort, it’s no surprise at all that capturing the liveliness of it in 3D graphics was a herculean task.

So herculean, in fact, that the designers at Pixar tasked with animating the curly and fiery hair of Brave‘s protagonist Merida spent nearly three years studying the physics of curly hair to get her larger-than-life mop to flow and bounce like real curly hair. In addition to their extensive study of curly hair, the design and rendering process alone was enormously time consuming: the scene in the movie where Merida removes her hood to reveal her hair took two months of dedicated work.

Thankfully, the work they did is transferable and what they learned modeling Merida’s hair can be used in future movies and to model other similar assets.