The wicha of using animal skin to make amulets is called GarnTamPhraNang
The skin that was used for making Takrut Nang Kwai Phuek, came from the skin of buffaloes that had been struck dead by lightning. The first batches were made from the forehead skin of an albino buffalo that had been struck dead by lightning. As the story goes, this particular buffalo had been involed in many Hae Nak, and Luang Phor comforted the buffalo, encouraging it to be reborn as a human being on account of the merits it had accumulated.
When the villagers attempted to dispose of the buffalo’s carcass with fire, they realized that it would not burn. Upon hearing of the phenomenon, Luang Phor surmised that the buffalo had offered its body to the Buddha. In recognition of this, he removed the buffalo’s forehead skin, to be made into amulets for the villagers.
Luang Phor Mon originally made the takruts to protect people from snakes, because the area was surrounded by forest and rice fields, and people would occasionally die from snake bites while farming in the fields or travelling on the road. They were distributed for free, but when the villagers began carrying them, they felt that it was effective at protecting them from other forms of danger as well. Word spread, and the takrut became famous. More people came to ask about the takrut from Luang Phor, but he was unable to make a larger amount, as the provenance of their material (having a white buffalo struck by lightning) was extremely rare. Because of the scarcity of lightning-stricken albino buffalos, he began to use skin from the remainder of the animal too. The forehead skin was still reserved for depictions of the Buddha, such as Somdej, while the rest was used for takruts.
After acquiring the skin, it was soaked in water to soften it. It was then cut into pieces, put into a Somdej mould, and pressed into a piece of bamboo until the materials fused. Some pieces of Somdej would comprise the entire piece of forehead skin. These Somdej were called Puttakoon Phra Somdej Nang Kwai Pheuk