How do you make a monster cuddly and lovable?

That was the challenge facing the makers of the new animated family movie “Smallfoot,” about Migo, a giant yeti, who meets a human TV host named Percy.

In the PG-rated film, out Friday, a village of adorable yetis fear people, whom they call “smallfoots,” and the mountain folk are frightened of mythical yetis, a k a bigfoot. But being in a movie that’s meant for kids, Migo (Channing Tatum) and his furry friends couldn’t be too scary.

“You’re trying to create an appealing character,” director Karey Kirkpatrick tells The Post. “Somebody you want to spend a lot of time with.” Here’s how the “Smallfoot” team turned a ferocious yeti into man’s best friend.

When we first meet Migo, he’s at home in his yeti safe-haven, surrounded by similar-size friends and family. Viewers love him instantly.

But when he meets Percy (James Corden), after tumbling down the mountain into a human town, he strikes fear. “We wanted him to be big and imposing [to people],” Kirkpatrick says. “Migo is the equivalent of 18 feet tall. Percy comes up to his kneecaps.” Moviegoers, however, have already warmed up to the yeti.

“There’s a few existing yetis in the zeitgeist,” says Kirkpatrick. “Like the Abominable Snowman in ‘Rudolph the Red-Nosed Reindeer,’ which I grew up with.” Unlike that freaky, retro creature — with sharp fangs, long claws and wild fur — Migo has normal, if large, fingers; rounded, slightly crooked teeth; and a cute fuzzy coat.

“The bigger the eyes, the more sympathetic the character,” says Kirkpatrick, citing beloved creations with huge peepers such as the title alien in “ET” and Puss in Boots from “Shrek.” Migo and most other mountain denizens in the film have them, too, and they’re specifically inspired by an old 2-D favorite. “ ‘Looney Toons’ characters with oval eyes became the visual language of all the characters,” he says.

Migo’s left horn is cracked in half. Though we never see it break during the film, the trait is the result of a scrapped prologue in which bullies pushed him to the ground. Kirkpatrick decided to keep it. “It makes him a little vulnerable,” the director says. “And visually, it just says he’s a little bit flawed.”

Much of what Migo says and does in the final film was inspired by the “affable, boyish exuberance” of Tatum’s voice, Kirkpatrick says. But even so, occasionally the “Magic Mike” actor had to be reeled in from making Migo sound too brooding. “I had to keep Channing in his upper register,” he says. “When he gets close to the mike, he gets a little too tough and a little too cool.

“If the lines got too tough, we’d say, ‘Not sounding like Migo there.’”