Machine Gun Kelly took to Instagram to share the process behind his massive torso blackout tattoo.

In the compilation footage he recently posted via an Instagram reel, he gave his followers a peek into what he went through to cover up his old tattoos -- seven intense tattoo sessions over two weeks, bloody arms, a swollen elbow and him using a hyperbaric oxygen chamber to heal faster.

Hyperbaric oxygen therapy involves exposing the body to 100% oxygen at a pressure that is higher than normal. As wounds need oxygen to heal properly, the chamber can speed up the healing process, per Johns Hopkins Medicine.

RELATED: The 'Spiritual' Reason Why Machine Gun Kelly's Tattoos Are Now Covered In Blackout Ink

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"This is the most painful s**t I have ever experienced in my life," he said.

According to Healthline, for men, high to severe pain can be experienced when getting tattoos on the armpit, nipples and breasts, elbows and stomach -- areas where MGK got inked.

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The rapper unveiled his blackout tattoo, which covered his chest and arms, in February, saying that it was for "spiritual purposes."

His tattoo artist, whom he tagged in his post, revealed in an interview that MGK's old tattoos were too chaotic for him now because he wanted "change and order" in his life.

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Roxx also shared that the "Bloody Valentine" artist's tattoo process started mid-December last year. MGK visited her private L.A. studio four times a week to undergo 13 six-hour tattoo sessions.

Meanwhile, during an appearance on the "Call Her Daddy" podcast, Megan Fox, MGK's on-and-off partner, shared her thoughts on the rapper's tattoos.

"He has a really special story behind why he did that, which obviously, I'll leave for him to tell. But the relationship with the tattoos that he had was very conflicted emotionally, whatever they represented -- and I don't actually know -- but he didn't like to revisit those memories of some of the tattoos that he had and wanted to get rid of them," she said.