One of the most stunning visuals from the first trailer for the upcoming live-action adaptation of the landmark anime Ghost in the Shell was a beautiful, unnerving robotic geisha. The robots look like perfect dolls on the outside, yet their faces blossom open to reveal a terrible high-tech visage underneath. Creating that uncanny look wasn’t easy, as seen in a new behind-the-scenes video.

Adam Savage of Mythbusters fame dropped by New Zealand’s Weta Workshop to speak with Richard Taylor about some of the work that the renown special effects company has done on the new film. Those ultra-robotic geishas were actually some very complex and intricate masks and props.

The masks, Taylor explained, were all modeled after Japanese actress Rila Fukushima. Weta’s designers scanned and made head casts of the 28-year-old actress and model, who is best known for her role in 2013’s The Wolverine along with appearances on Arrow and Game of Thrones. Then, to make her face seem more artificial, they made it symmetrical, getting rid of any possible imperfections (aka, the stuff that makes us human).

Taylor said it was a bit of a struggle to make sure that other actors’ heads could fit into masks based on Fukushima’s features, especially since many of the actors wearing the roles had western features.

Rila Fukushima, the actress that all the Geishas are based on.

Taylor also detailed props, including battle-damaged versions of the geisha heads or models that opened up to reveal the clockwork machinery underneath. The way that the face opens up, he said, looks simple but was actually extremely hard to get just right.

“A car door is a surprisingly complex thing to make,” he said, comparing them to the geisha’s multiple segments.

Watch the video below, and look for Ghost in the Shell when it opens on March 31.

Photos via Getty Images / Thomas Lohnes, Tested