Simply by adding a set of multiple sub-injection molders to an existing injection molding machine, coupled with a delicately-designed mold core rotating mechanism, it will enable the machine to produce product of various colors or materials through the same injection molding procedure, a means to satisfy the demand for variety in craftsmanship. While significantly increasing the intensity of the product as a combination of various materials, it shortens the production period and molding cycles. Traditionally, it needs several differing molds to make such products which now requires only one well-designed mold to produce. Now, less molds are required and production cost would be cut accordingly.