In the short documentary, Downey can be seen briefly explaining his gestures. To “activate” the magnets in his body, Downey decided, he would raise his right index finger with his left fist clasped behind his back. That, he said, was a gesture indicating that he was in control. Then, to summon the first piece of armor, he held his right elbow at a 90-degree angle from his body, keeping his fist aloft, while thrusting his left arm forward, palm up. After catching a few pieces on his body as a test, Downey then held up two “hang loose” gestures (hands raised with pinkies and thumbs extended) to summon the rest of the pieces all at once.

The documentary then proceeds to show how Downey was thrown around the room — using mostly cables and pulleys — as the pieces of armor hit him. The armor was animated with CGI, so Downey not only had to invent the gestures but also do some extensive mime work, imagining that certain pieces of the armor were already on his body.

In another parallel to in-film details, the SFX technicians had to pepper Downey’s body with motion-capture points to animate the armor on him after the fact. The motion-capture points were located more or less where Tony implanted the magnets.

Later in the film, Tony Stark is kidnapped by the movie’s Big Bad and handcuffed to an upright bed frame in a dingy warehouse. Luckily, the gestures still work even when he can’t move his arms, and Downey only needs to flick his hand open to summon his armor.

There were still limitations to the flying armor, though, which made “Iron Man 3” fun and interesting. It’s one of the best films in the Marvel Cinematic Universe.