Qualley tells PEOPLE how the body-horror film, directed by Coralie Fargeat, pushed her to take risks onscreen Embodying her character in The Substance challenged Margaret Qualley to take new risks onscreen.

Due to time constraints, Persin subcontracted the build of Monstro Eliasue’s suit to a U.K.-based company. “We had two full suits, one for a stunt double, and a half-built suit for Margaret, which she wore for closeups.” Persin and his team took care of all the effects, including the boob that squeezes out of one of Monstro’s many holes.

Demi Moore tells PEOPLE she hadn't met Margaret Qualley before becoming her costar in Coralie Fargeat’s new horror movie 'The Substance,' but had enough 'indirect connections' that they 'felt like we

Obviously, between all of the scenes of spine-splitting, vomiting, close-up injections and Dennis Quaid chowing down on a plate full of prawns, the whole film wasn’t exactly a walk in the park, but there was really no preparing for the birth of Monstro Elisasue in the final act, was there?

Full of bold colors, detailed close-ups, and tearing flesh, “The Substance,” directed by Coralie Fargeat, takes body horror to a new level. The commentary on Hollywood’s treatment of women and the concept of “aging gracefully” can’t go unnoticed.

She and costar Margaret Qualley also devoted time to perfecting sexualized gyrations their celebrity fitness characters would perform in front of leering cameras and a slimeball of a boss, played by Dennis Quaid,

Demi Moore, Margaret Qualley and Dennis Quaid attend the premiere of their upcoming film "The Substance," at the Directors Guild of America in Los Angeles on Monday. The film, which hits theaters on September 20,