The 1933 King Kong puppets used Rabbit Fur which was glued onto (covering) the built-up rubber sculpted muscles (the Kong puppets). Willis O'Brien was the overseer of the King Kong special effects and also the primary stop motion animator. Marcel Delgado did the taxidermy fabrication of the Kong puppets. Because the fur-hair was somewhat thick, when Kong was animated, the fur would show the animators 'finger depressions' on the fur. When the animation was completed & played back, the fur had a rippling movement effect to it. To help address the fur issue problem with the stop motion puppets, a method for "rubberizing" the fur was invented by taxidermist George Lofgren who had, in years before, worked with Willis O'Brien.
This was the general process: First, the fur pelt was stretched on a frame.The fur was combed and then immersed in hot melted wax which was allowed to cool and harden. The fur pelt was then placed into an aquarium type container (with a cover) or an enclosure, or box. Into the enclosure, a specialized insect larva ... the Dermestid Beetles Larvas, were added. These insect larvas devour & eat away, all the exposed hide (leather skin). It may require hundreds of these beetles to accomplish the hide removal. Higher numbers of the beetle larvas will remove the hide-skin more quickly.
After all the hide was removed by the Dermestid larvas, only the exposed root ends of the wax-embedded hairs were slightly protruded & visible. Larvas will eat just about anything organic but they do not consume the 'Hairs'. Liquid latex rubber was then brush coated onto all the root hair-fur ends. When the rubber coating cured, the fur was now bonded to the thin latex rubber skin-like layer. To remove the hardened wax from the fur, repeated flushes of boiling hot water was used to soften & melt away the wax. The treated rubberized fur was then combed, trimmed, then applied, glued onto the puppet model.
The "rubberized" hair, was now highly flexible and after applied to the puppet model ... when the fur was touched, it would spring back into place, lessening the rippling effect whenever the puppet was re-positioned & handled during the frame by frame animation.
This is an OLD technique which I think, is not used anymore for creating flexible fur pelts. I believe, you can now buy synthetic hair pelts that are adhered to a stretchy material, similar to spandex. However, Dermestid larvas are still used in the field of archeology and taxidermy where skulls, bones & skeletons need to be thoroughly cleaned.