This paper reports on findings from a group of ten teachers who were enrolled in a semester-long, graduate-level educational technology course that used design-based learning to explore the integration of making and the engineering design process into a variety of K-12 educational contexts. Using convergent mixed methods, this study examines how the course impacted teachers' familiarity and confidence in teaching the engineering design process, as viewed through their pre- and post-semester engineering design self-efficacy scores and their weekly reflective journal entries. These measures are important factors for developing teacher experience and confidence in integrating engineering and design-based learning strategies within K-12 educational contexts. Statistically significant results include increased confidence in design and decreased anxiety toward design. Findings illustrate how participants acknowledged increased familiarity and confidence in teaching the engineering design process, including their increased ability to make connections to the engineering design process, maker tools, and techniques. Implications for teacher education programs are discussed.