the plastic substrate portion of the part is formed by a first injection of plastic into a mold , so as to adhere to an overlying sheet of coverstock material . a portion of the coverstock is not initially adhered to the substrate . a second injection of plastic forms the undecorated portion of the part , and bonds to the substrate portion to form a unitary plastic panel . in the course of contacting the substrate portion , the plastic from the second injection folds and hides the non - adhered portion of the cover stock , thereby forming a neat , clean split line .