The Framework for K-12 Science Education and the Next Generation Science Standards (NGSS) underscore the importance of including engineering design process (EDP) within the science curriculum. The Framework and the NGSS raised engineering design to the level of scientific inquiry in an attempt to prepare a STEM-literate workforce for the 21st century. Science teachers and elementary teachers do not have the required pedagogical content knowledge and self-efficacy to integrate engineering design in their own teaching. We believe that preservice elementary teachers should be taught how to integrate the EDP into their teaching and think that introducing 3D printing into preservice elementary science teaching methods courses can be an effective method for integrating engineering into elementary science teaching. In this study, our purpose is twofold: (a) provide a detailed explanation of how 3D printing is integrated into the EDP within the context of an elementary science teaching methods course and (b) investigate the changes in preservice elementary teachers' engineering teaching efficacy beliefs as a result of their participation in an engineering design challenge that requires 3D printing. Our results revealed an increase in PST engineering teaching efficacy beliefs.