“America has been tortured enough already.”

But alas, not Mandy Moore. It’s the last day of filming on Season 2 of “This Is Us,” and for the sixth time on the finale’s eight-day shooting schedule, Moore begins her day in the hair-and-makeup trailer, girded for the three-hour process that will turn the 33-year-old actress into the 68-year-old Rebecca. Moore estimates she’s gone through the transformation more than 30 times — 20 this season alone.

Not that she’s complaining about it. “I love that I’m given this opportunity to play this character from 25 to 68,” she says. “That’s so unheard of. So I don’t begrudge the process that comes along with it.”

The finale chronicles the wedding day of Rebecca’s daughter, Kate (Chrissy Metz), and Toby (Chris Sullivan), which means the present-day action calls for Moore’s near-daily transformation. Given the death of her husband, Jack (Milo Ventimiglia), Moore’s Rebecca is the only character who exists in all of the show’s multiple timelines: from the 1980s when she and Jack first meet, through the ’90s when they’re juggling tweens (her favorite age, she admits) and then teenagers, to the present, where she’s remarried and trying to resolve long-simmering issues with her three adult children.

“It’s such an honor to be the glue of this family,” she says. “I feel a tremendous amount of responsibility.”

Playing older Rebecca she says is the most challenging age, not just because of the labor-intensive process but also because of the deep-seated emotion it inevitably carries. “If I’m in age makeup, something dramatic has happened,” she says. “I’m being confronted by my son about the fact that I’ve been lying to him, meeting his biological father and pretending I don’t know him, talking about the anniversary of my husband’s death.”

Even amid all of the show’s mysteries, the transformation is “one of the most asked-about questions,” she says.

The hair-and-makeup trailer is well lived in, fitted with six chairs for the actors and crammed with mementos of an intense season. Taped on the walls are photos of the cast in a range of stages (tracking Jack’s famously fluctuating facial hair), as well as a chart listing their relative ages through the show’s complicated timeline. Jack’s stops abruptly in 1992.

There’s a jubilant feeling of senioritis in the air — everyone’s talking about the wrap party, set for the following night. The set is also abuzz about paparazzi photos that were leaked the day before, and crew members debate camera angles to try to identify the culprit.

Throughout the morning, other stars filter in and out of the trailer — Metz, Justin Hartley (Kevin), Caitlin Thompson (Madison). Ventimiglia is on set, too, even though he’s not filming, to lend his support: “Someone made some money,” he says regretfully of the spoiler-laden photos.

They’re accustomed to Moore’s lengthy stay in the trailer, but they know all too well their time might also be coming. We’ve gotten a glimpse of future Randall, which means Sterling K. Brown spent about four hours being transformed. He’s on deck for another session later in the day.

And those leaked photos revealed that another of the show’s stars had his turn too. “It gives me a kernel of satisfaction that other people now know what it’s like,” says Moore with a sly smile.

Moore arrives in the trailer promptly at her call time of 8 a.m, her long brown hair still wet from a shower, clad in a robe, jeans and Uggs and carrying boxes of croissants from a favorite bakery. (None for her, though — she’s gluten-free.) On cue, hairstylist Katherine Rees first offers her conditioner, then Advil. It’s not that she’s hungover; she’s preparing for the headache that inevitably comes as her hair gets pinned up ever so tightly. Moore gratefully accepts the pills as hair department head Michael Reitz wraps her hair around her head to fit under the wig cap, the first and easiest step in what will ultimately be a nearly three-hour-long odyssey.

Fifteen minutes later, she moves to the makeup chair for a far longer haul, and turns on the timer on her phone, ever hopeful that this time things just might be quicker.

Crafting the right look for older Rebecca was an ordeal of its own, with several tests that went too far — inflated lips, a floppy neck waddle, long gray hair.

“We went to 12 and had to bring it back down to 6,” says makeup department head Zoe Hay, who’s worked on shows like “The People v. O.J. Simpson: American Crime Story.” “We came at it with the least we could do, but had to keep stepping it up to find what really works.” Paramount to the effort was maintaining a sense of continuity about Rebecca’s naturalistic style. Twentysomething Rebecca might be more playful with color (“A young woman would experiment with how she looks,” says Hay), but as she ages, she settles down into more neutral, safer choices.

What solved the problem were some leftover prosthetics from makeup artist Stevie Bettles that Hay happened to have in her trailer from a recent commercial shoot. They’re impossibly thin silicone stickers, color-matched to Moore’s skin and placed precisely around her face and neck.

“Her gestures are completely different … in terms of there having been a fair amount of tragedy and sadness in her life. She carries it all. And that was not something I ever discussed with her.”
Dan Fogelman

She can still emote through them — an important detail, given all of the crying Rebecca is wont to do — though Moore reveals she doesn’t know when tears are running down her face. “It’s a very weird sensation,” she says. “Sterling told me I was crying last night, but I couldn’t feel it.”

The team knew it had finally found the right look when Moore shot a scene with Ron Cephas Jones (William), who’s 61, and it played seamlessly, as if she were truly the same age as he.

“This Is Us” showrunner Dan Fogelman says he briefly considered casting two actors for the role (à la “The Crown,” which is replacing Claire Foy with Olivia Colman as the queen ages), but that scene with Jones proved he was right to trust his “gut instinct” of letting Moore pull it off alone.

“Her gestures are completely different; her voice changes; her shoulders carry the weight of a life lived hard — not in terms of drugs or alcohol, but in terms of there having been a fair amount of tragedy and sadness in her life,” he says. “She carries it all. And that was not something I ever discussed with her.”

Before the prosthetics can be applied, though, Hay — along with makeup artist Elisabeth Chang — begins the process of wrinkling Moore’s normally clear, smooth skin, painting on speckles and age spots and delicately applying an ager onto her skin and hands that will form lines and creases. As one dabs, the other pulls her skin tightly; Moore’s coloring turns red as they poke and prod. (Removing it all at the end of the day will take another 45 minutes to protect her skin: “We call it the devil’s glue,” says Chang.)

It’s a well-choreographed dance; Hay and Chang are careful not to bump into each other in the cramped trailer, and Moore doesn’t need to be directed which way to turn her face, when to stick her thumb in her mouth to stretch it out, or when to turn herself nearly upside down in her chair, so they can paint under her neck. “The first time I was like, ‘You want me to do what?’” she says, laughing.

They move painstakingly from her eyes to her forehead to her lips, where Hay paints on additional delicate lines, erasing the lips’ natural edge. “Smoke and mirrors,” she says.

After an hour, they take a 10-minute break before moving on to the prosthetics — there are 10 in all. (Four for her eyes, two for her laugh lines, two jowls, one neck piece, one for the bridge of her nose.) “It’s like putting on a Band-Aid, but not quite,” says Hay as she peels each one off the board they’re all pinned on. After she carefully puts them in place, she brushes over them to melt them into Moore’s face and neck.

The rest of her body is spared — if Moore has her way, we’ll never see older Rebecca’s legs or feet. “I hate wearing panty hose, but I will wear them every single time I have to be older Rebecca,” she says. Nor will we ever see her in a bathing suit. “That would have to be a body double,” she says with a laugh.

One thing remains constant: Her nails at every age are always a light pink. “It’s the last thing I want to think about,” she says.

They’ve had to navigate a few unforeseen challenges — when Hay broke her hand and three people had to fill in, or when Moore banged into the shower door, and they had to cover up her black eye. Luckily it was the Halloween episode, so Rebecca as Cher sported purple eyeshadow.

Each character has a detailed bible with his or her history, and one crew member is tasked with maintaining continuity. Given the show’s tendency to jump back and forth in time and revisit past scenes, each look needs to be carefully tracked.

When Hay is ready to put the tiny crow’s-feet prosthetics on Moore’s eyes, she yells out: “Eyes! We’re doing eyes!” That’s a signal for everyone to stop moving — no one steps in or out of the trailer as she applies the stickers. “The miracle is me not sticking myself to Mandy,” says Hay. “That may or may not have happened before.”

Matching Moore’s face side to side is the trickiest part, and Moore points out that one eyelid feels heavier than the other. There can be no cheating. “They like to put the camera everywhere,” complains Hay. “The cameras are not our friends.” She inspects her work through a magnifying glass, looking for spots she might have missed. At least today’s shoot is indoors; daylight makes matters worse. “When they shoot outside, it gives me a heart attack,” she moans.

And then Hay layers on the usual stage makeup, but she has one more trick up her sleeve: frosted eyeshadow. “It shows every wrinkle,” she explains. “You wouldn’t want it as an older woman, but it helps Mandy.”

Finally it’s back to Reitz for the wig. With eight precisely planted pins and more application of glue, he secures the stylish yet age-appropriate bob on her head.

Says Moore with a satisfied look in the mirror: “There she is.”

Credit that senioritis: They’re done in near-record time, just under three hours, and Moore’s finally ready for her close-up.

Director Ken Olin leads the cast through a rehearsal, figuring out their marks. It’s a short scene, but the quick exchange between Rebecca and Kate speaks volumes about the tension in their relationship.

“Did I say something wrong?” Rebecca asks her sons after the encounter sends Kate marching out of the cabin.

“I feel so bad for her,” Moore says of Rebecca after the scene has wrapped, over lunch in her trailer. (There’s a pizza truck on set, but she opts for a healthier salad of grains and fish.) “She’s so acutely aware that she ruffles Kate’s feathers, so she’s trying to be on her best behavior. I see myself a little bit in my relationship with my own mother. It’s very complicated.”

And while audiences have focused on Jack and his death, Moore hopes that they’ll come to find sympathy for the character, too, even if she has made questionable choices.

“I have a real soft spot for her,” she admits. “She’s just not the same. The life force is out of her eyes. Is it just Jack? It has to be, but she breaks my heart.”