A composite thread protector that will be practical under normal as well as frigid temperature conditions of usage is formed by deep drawing a seamless metal shell wall, using a threaded die to define a mold cavity with the metal shell wall, forming and setting a synthetic elastomeric shell wall within the mold cavity in an adhering assembled relation with and along the metal shell wall with threading that is complementary with threading of the die, removing the assembly by unscrewing it with respect to the threaded die, and subjecting the assembly to heat treatment to cure the elastomeric shell wall and provide a composite protector having a cast urethane elastomer wall in a secure adhering encapsulating relation on the metal shell wall.