Cranioplasties are procedures that use custom implants to restore the protection that the skull provides to the brain and improve the appearance of the surface after having suffered a defect in the cranial vault. These implants provide excellent aesthetic results to patients; however, the objective of our research was to improve and propose a new methodology for manufacturing cranial implants using materials such as polymethylmethacrylate (PMMA) and printing molds with flexible resin for the manufacture of these using 3D printers. Our project was born from the need to create personalized implants at low cost and with a new material for the mold that facilitates, speeds up, and reduces the price of this procedure. To show our new methodology, we propose to reduce the cost of implants, the time, agility, and cleanliness at the time of the process when manufacturing the molds for cranioplasties, and thus reduce surgical time, greater efficiency, and refine results at the manufacturing time.