"It was by far the largest puppet we ever created. It seemed insane," says VFX supervisor Steve Emerson.

Laika, the Oregon-based stop-motion animation house, usually films its movies using hand-crafted puppets that are just six to 12 inches tall. But for its latest film, Kubo and the Two Strings, which Focus Features will release on Aug. 19, it went in the opposite direction, creating an 18-foot tall stop-motion puppet that's believed to be the largest ever of its kind.

“It was by far the largest puppet we ever created,” VFX supervisor Steve Emerson said Monday at the SIGGRAPH Computer Animation Festival taking place at the Anaheim Convention Center, where the Kubo filmmakers offered a behind-the-scenes look at the making of the movie. “It seemed insane, so of course we did it.”

During one scene in the Japan-set fantasy-adventure, the protagonist Kubo (voiced by Art Parkinson), Monkey (Charlize Theron) and Beetle (Matthew McConaughey ) come under attack by a giant skeleton — a huge challenge for Travis Knight, the Laika CEO who was taking ahold of the directorial reins for the first time, and his team.

“We were initially going to build a small, manageable skeleton," said camera and motion control engineer Steve Switaj, but that created a problem of scale since it had to appear alongside the other puppets. After considering such options as separately building the hands and other parts of the skeleton that would be needed at large scale, the team concluded they would need to build an entire oversized puppet.

They tried motion control. They tried a giant robot. In the end, the puppet was built on a hexapod robot. Its nine-foot arms needed support, and were effectively puppeteered by a motor-driven system. It all took six months to build.

Then came the stop-motion animation process. "It was incredibly slow to animate," Emerson admitted, saying that photographing the puppet frame by frame resulted in just one second of animation after a week's work.

Kubo is actually described by Laika as a hybrid film since it also involved the use of digital elements and effects to capture the scope of the story. “Stop-motion films are extremely difficult to make," Emerson explained. "We want to tell big stories, and we don't want to make concessions. We embrace [digital] technology, but we try to stay true to stop-motion so it looks hand-crafted.”

For Kubo's big scene, the giant skeleton was built on a greenscreen stage, where it could interact with the other, much smaller puppets during the shoot. The characters were then composited into the film's Hall of Bones setting. For that set, the floor and lower part of the room was built as a practical set. The top was a CG extension, reported Eric Wachtman, CG look development lead. Additional CG elements and effects were added to complete the sequence.

Prior to its release, Kubo and the Two Strings also will be showcased in “From Coraline to Kubo: A Magical Laika Experience,” an interactive event that will be held Aug. 5-14 at Universal Studios Hollywood’s Globe Theatre.