Even before the script for King Kong was completed, Cooper started filming action sequences with Fay Wray and Robert Armstrong during breaks in the filming of The Most Dangerous Game (1932), which also had a jungle setting.

The 18-inch models of Kong built by Willis O'Brien's assistant, Marcel Delgado, were the first animation models with metal skeletons and joints. Instead of the jerky movement of models built on wood, Kong moved much more smoothly, creating a greater illusion of life. Delgado covered the skeleton with rubber muscles that actually expanded and contracted as they were moved. The creature was then covered with rubber and latex skin and rabbit fur.

The animated models had to be shot one frame at a time, with minute adjustments between each shot. It often took an entire afternoon to get the 24 exposures needed to fill one second of screen time. The battle between Kong and the pterodactyl took seven weeks to film.

Most sequences in King Kong had to be shot non-stop, often requiring 20-hour workdays. Sometimes the shrubs used to dress the miniature sets actually wilted during filming. At one point, one of the plants on the set flowered. Before a scene could be started, all the lights on the soundstage had to be replaced with new ones to make sure they wouldn't flicker during the scene. The stage had to be sealed, and nobody could leave or enter to prevent any wind from moving the foliage.

Each night, the Kong models had to have their skins removed so Delgado could tighten the hinges on the metal armatures.

The one flaw that remains in the animation is the way Kong's fur seems to be moving constantly, showing where the animators had to grab the figure to move it.

O'Brien used three techniques for scenes uniting actors and models. The standard, at that time, was to film the actors in front of a projection screen with the effects footage. That was used for Kong's fight with the tyrannosaurus and the scene in which Carl Denham shoots the stegosaurus. O'Brien could also matte together actors and models in an optical printer. For those scenes, like the fight with the pterodactyl, Cooper shot the actors first, then filmed the models with the actors' side of the screen matted out.

The third technique was Cooper and O'Brien's innovation for King Kong. Cooper filmed the actors, then O'Brien projected the image one frame at a time on a screen behind the models. That's how they filmed Kong's removal of Wray's clothing. Originally, Cooper had wires attached to her clothes to pull them off her body. The model's movements were then matched to hers. Unfortunately, O'Brien and Cooper forgot to patent their approach, thereby losing a fortune.

In addition to the models of Kong, O'Brien had a 20-foot high head constructed. Three men sat inside it operating various levers to change the facial expression. Other body parts used in the film were a giant foot, to show Kong trampling people, and a giant hand for close-ups of Wray struggling in his grasp.

For the scenes of Wray in Kong's hand, the hand was attached to a crane and raised ten feet. First a technician put her in the hand and closed the fingers around her. Then the hand was lifted for filming. She would later say her terror in those scenes was real. The more she struggled, the looser the hand's grip grew. When she thought she was about to fall, she had to signal Cooper to stop filming.

After completing her scenes in King Kong, Wray spent a day in the sound studio recording a series of screams she dubbed her "Aria of the Agonies."

It took a year after the actors were finished for O'Brien to finish the effects work and Cooper to get the film put together. Between her work on King Kong and the film's release, Wray made four other films.

According to legend, one of the film's most spectacular scenes had to be cut because it upset preview audiences so much they couldn't focus on the next few scenes. Lost forever is a scene depicting the fate of the crewmen Kong shakes off a tree bridge. Originally they landed in a valley where they were attacked by giant spiders. Recently discovered memos from Cooper suggest that the scene was actually cut before previews because he felt it slowed the film down. The lost sequence inspired a scene in the 2005 re-make.

by Frank Miller