The kooky caveman characters that come to life in "Early Man " have been kicking around in Nick Park's imagination for decades.

Long before he created Wallace and Gromit, Park was taken with Ray Harryhousen's animated dinosaurs in the 1966 Raquel Welch movie "One Million Years B.C."

"I just couldn't believe real dinosaurs moving around with people," Park said, recalling the film he saw as an 11-year-old that would inspire his love of animation. "So I guess that sort of thing has been in the back of my mind for many years."

"Early Man" translates Park's vision into an epic claymation adventure about a tribe of colorful cave people who stake the future of their homeland on a soccer showdown, despite not knowing how to play. An ambitious young caveman, Dug, and his loyal pet warthog, Hognob, believe the plucky tribe can prevail.

"I've never seen a prehistoric underdog sports movie before," Park mused.

U.K.-based Aardman Studios tapped its largest production team yet — with nearly 40 animators and sets working at once — to make "Early Man," which uses stop-motion animation techniques essentially unchanged since Harryhousen's day.

It's a slow and painstaking process to bring clay characters to life.

"We've used some of the most advanced filmmaking techniques in post-production, together with stop-motion, which is as old as cinema itself," said animation director Merlin Crossingham.

Stop-motion animation (or "stop-frame," as Park calls it) creates the illusion of movement through a series of still images. For "Early Man," Aardman's team of artists built a cast of puppets based on Park's sketches that serve as the film's actors. Each seven-inch-tall silicone puppet has a jointed metal skeleton inside so it can move.

"They're like expensive action figures," Crossingham said.

The faces are made of modeling clay — except for the noses and eyes, which are hard plastic and serve as "grab points" for animators while changing the puppet's expression. Moldable brows and more than two dozen removable and interchangeable mouths allow for a variety of looks.

Animators pose the puppets for each frame — every movement, every gesture — with 24 frames in each second of film. Mouth movements are synched to pre-recorded vocal performances. (Eddie Redmayne, Tom Hiddleston and Maisie Williams lend their talents here.) For every shot, the puppets are bolted into place on exquisitely detailed sets that stand about two feet high.

Capturing just a few frames could be a full day's work.

"Getting about five seconds of finished film is a really good week," said animation director Will Becher.

Because the process is so time-consuming, artists make duplicates of every set and puppet so multiple animators can work on various shots simultaneously.

"The art department has to be really on their game keeping the continuity," Crossingham said. "Because of that, we use technical drawings for everything — the puppets, the locations. Everything is documented so that we can reproduce it, and that gives us flexibility in working."

To show the disparate team of animators just what they're looking for, Park, Crossingham and Becher act out each scene on video, highlighting comic timing and behavioral specifics. Park confessed that sometimes he can see reflections of himself in the characters' movements.

As director, he was involved with every aspect of "Early Man," from character and story development to finding just the right color for the soccer field's grass. Park also personally worked with the vocal performers, something he wasn't always comfortable doing.

"I used to find it quite nerve-wracking working with actors, especially if they were quite famous actors," he said. "I find it much easier to manipulate a puppet or a clay character, because they do as they're told. And if they don't, you can squish their head in or whatever you want. With actors, you have to be a little bit more tactful."
Park voiced Hognob himself.

While the techniques of stop-motion animation haven't changed much since their inception, the technology around them has. The puppets are now made of a state-of-the art plasticine material, and most sketches and renderings are done in the computer.

As for the film itself, Park said he tried to use as little digital intervention as possible: "It's always lovely to keep the sense of it's all been done in front of camera and not an effect." Background characters in stadium scenes were computer-generated, he said, while other scenes called for the puppets to be filmed against green screens.

Park may have been dreaming about "Early Man"-type characters since he was 11, but his first sketches for the film date back to 2010. Still, that's nearly eight years spent bringing these bobbling clay cave people to the screen. Park said imagining the audience's eventual reaction is what sustains him through the sometimes tedious work of stop-motion animation.

"For me, it's never really been a choice between stop-frame and any other medium," the four-time Oscar winner said. "I love the way it's so expressive — even going back to Gromit, he was born out of clay.

"It's the fact that the animator has to do the brow or whatever it is, just to tease out the character frame by frame. There's a certain quality to do with nuance and acute human observation," Park said. "It's often the very small things that really win the audience over, because they see somehow themselves or their friends in that character. I love the way you have a real puppet and you can light it with dramatic lighting, just like any movie. It just feels very real and very special."