Most movie audiences think of miniature work in terms of special effects, like the scale models Industrial Light & Magic built to create the Death Star trench run in Star Wars or the model of Helm’s Deep used in The Lord of the Rings: The Two Towers. In Ari Aster’s Hereditary, however, they’re actually part of the story. Annie Graham (Toni Collette) is a diorama artist, and the detailed reproductions she makes of traumatic events in her life initially serve as a catharsis, then eventually document the decaying state of her fragile mind.

The person responsible for creating those pieces was model and miniature designer Steve Newburn. A visual effects veteran who’s done model work for movies like Inception and The Dark Knight, Newburn is a dual threat who’s also built a career in prosthetic makeup work on projects like Suicide Squad and Guillermo del Toro’s vampire TV series The Strain. (He handled Hereditary’s grisly corpses and makeup effects, as well.)

The morning after he saw the film for the first time, I jumped on the phone with Newburn to talk about the creation of Hereditary’s haunting miniatures, his collaborative process with director Ari Aster, and the creation of some of the movie’s most disturbing makeup effects.

Warning: significant spoilers for Hereditary below.

This interview has been edited and condensed for clarity.

How did you first get involved with Hereditary?

I have a company in Toronto. I’m from LA, but my wife’s Canadian, and we came up to Toronto about 10 years ago. I was doing a lot of prosthetic work with Guillermo del Toro. I got contacted about the prosthetic side of things on [Hereditary] and was forwarded the script, went through it all, and just threw it out there, as a question of curiosity with Ari when I first spoke to him: “Who’s doing all this model stuff?” He was just like, “Well, why? Do you know somebody?” And I said what I originally got into the industry for was a fascination with model and miniature work, and I spent years working on that side. So it just turned into one of those things where both of them fell in my lap.

What were your initial impressions of Ari? His shorts have such a distinctive voice, but you were talking about working with a first-time feature director.

I liked his enthusiasm. You work with a lot of directors in the industry that come in and say they’re passionate about something, and then you actually start dealing with them, and you can tell that’s kind of a lie. I don’t want to name names, obviously, but I’ve seen a lot of that over the years. So this one, because he also wrote the movie, I was like, “Okay, this guy. He’s going to be passionate about it because it’s his own baby.” But I spoke to him on the phone for maybe half an hour. He was a walking cinephile when it came to information and whatnot. You could tell the guy was really into everything he was trying to get done here. Everybody says this, but I genuinely read [the script] and went, “This is actually really crazy good.”

You’re so used to seeing Saw movies and silly “horror films” with teenagers running around being stalked. I liked the fact that it was a character-driven thing, hearkening back to Rosemary’s Baby, The Omen, the ’70s, and the way horror movies were done back then. That really appealed to me. So we connected in a restaurant, chatted about it, and he just exuded passion. From my perspective, the easiest people to work with are the people who are into their project. You can tell they are. Working with Guillermo del Toro was the same, where he’s such a fanboy at heart, you can’t help but just want to be there and do the best possible work. Ari exuded a lot of that same thing.

A miniature is the first thing the audience sees in the film, and it’s incredibly effective at setting the tone from the beginning. What was the design process of the models like from script to shooting?

Ari had a list already established of what he was hoping to see for all the main ones. He knew there were locations within the script that he wanted to do models of, based on the story. A hospice because Annie’s mother had been in a hospice right before she passed away. He wanted to do the funeral home where they had the funeral for her mother. He wanted to do a preschool that [her daughter] Charlie, in theory, would have gone to a few years earlier. He had this list of things he wanted. There weren’t really designs for any of them, because some of them were going to be based on locations, and others weren’t going to be featured as locations within the context of the movie, and were just open to suggestion. So we broke the list in half, initially, which was featured locations from the movie, [and then] non-featured locations.

It’s a tremendous amount of stuff. Not to build the structures, so to speak, but to furnish it and put all the details into it. So my suggestion to him was basically, “Let’s get started on these ones where we don’t need to know what the locations are.” I did little CAD models of the preschool, the hospice, which you didn’t actually see, and a couple others. And basically just started pulling reference images off the internet of preschool décors. It’s the typical “feel [a client] out and see what grabs them” process. Sending him lots of images, “What appeals to you in this image, what doesn’t appeal to you?” etc. Getting his feedback, and then cobbling something together. Scale was an issue. We settled on 1:12 scale. His initial list was interesting. He said, “Oh I want a hospice, and I want it to be 1:6 scale,” or something like that. I was like, “Well, you realize that a 6th-scale structure means a person is 10 to 12 inches tall?” We’re sitting in this restaurant talking about this, and I’m like, “You know, a wing of a hospice could be the size of this restaurant, even in miniature.” And I think that’s where he went, “Whoa, okay. Yeah, that’s not going to work.”

Then this thing came up of maybe we should add in pieces from [Annie’s] previous exhibit [from] a few years earlier, so we started building some other little “throwaway pieces” for that, which are actually highly featured in the movie. There’s what we call the “quicksand model.” It was three houses sinking into the earth. It’s right by the staircase going upstairs [in the Graham house]. There’s another little two-story house that’s right in front of the front door. You don’t really see it in the movie, but all the doors and windows have chains and steel plates over them, and vault doors. It was a good combination of “What can we do for the time we have, what can we do for the money we have, and what realistically will fit?” And even there, I think it was underestimated how much space [these pieces] would take up.

A big part of the conversation once Grace Yun was hired as the production designer was, “What is Annie’s artist’s loft? Is it a converted garage? Is it a room in the house?” And this was at a point where they were also looking at everything being shot on location. So where do you find a space where you have 1,500 feet of space that could be her workshop? Ultimately, everything ended up being built onstage, so that was accommodating for them. But even then, it was still all squeezed in there really tight.

Several of the miniatures in the film are rooms in the actual Graham house itself. What were the challenges of making those match as closely as possible?

It got really crazy how last-minute everything became because a lot of what I had to do was based on what they were doing full-sized for the sets. So my team, we were literally 11th hour during the whole production, trying to get that stuff done. The sets, because they were last-minute as well, we got the structure, but you never knew what the details were going to be inside of it. We were building into the shoot, and I’d go down there to shoot a body or something, and they’d be laying a parquet floor. And I’d be like, “Oh, okay. I guess we’ve got to do that now! Oh, everything’s got wainscoting and panels on the walls. Now we’ve got to do that.” Matching wallpaper samples. It’s all very run-of-the-mill for miniature and model building, but I don’t think really ever under this kind of timeline pressure.

It was great to see the movie and how well [the model art] was featured. Ari had always said it was going to be highly featured, that he almost considered it a character in the movie in and of itself. But, you know, to actually see it last night and be like, “Oh, yep. There it is!” And even there, you don’t see three-quarters of what we did.

Your team is behind one of the most disturbing images in the entire film: Charlie’s severed head after she’s killed. How did you develop that effect?

It’s toned down significantly, the decapitation. We had built entire puppets that the heads came off of, and squished, and blood went in every direction. It was all shot. It was pretty brutal to watch. I can’t say exactly why it’s edited the way it is [in the final film]. I think from talking to Ari at the time, he was like, “I don’t know if we can actually show that. It’s a kid, for God’s sake.” But then to follow it up with the aftermath the next morning, I’ve heard a number of people say that’s just revolting to them. Mostly because of the ants.

So we had that stuff, we have a lot of little smaller things that aren’t seen so much. But we did the body of Toni. Toni sawing her head off, things like that, which is all prosthetics as well. Done practically, no CG.

The body of the grandmother up in the attic, which funny enough is [a cast of] the mom of Kayla Dobilas, who was my key on the show. We were in Toronto at the time, and I had to build this body of [the grandmother], but the actress wasn’t available to us. I think she was a local in Utah. So who do we have? Kayla was like, “Oh, we’ll get my mom in.” So we made a rotting, headless corpse of her mom. [Laughs]