<p>The aim of this study was to explore the impact of models individually prepared by preservice teachers for the topic of solar and lunar eclipses on their STEM-technological pedagogical content knowledge self-efficacy and their perception of self-efficacy in engineering design skills. In this context, our exploration was carried out in 2 × 2 factorial experimental design with 31 preservice science teachers in their last year of training. Accordingly, 16 preservice teachers were assigned to a modeling group that would use tangible materials and 15 preservice teachers to a group that would use Tinkercad. Data for the study were collected in the form of a pre- and posttest with the STEM-Technological Pedagogical Content Knowledge (STEM-TPACK) Self-Efficacy Scale and the Engineering Design Skills Self-Efficacy Perception Scale. The data were analyzed with the ANOVA test for two-way mixed measures. Our findings revealed a significant difference in the participants’ STEM-TPACK self-efficacy in favor of the Tinkercad group. On the other hand, no significant difference was found in the perception of self-efficacy between the two groups in terms of engineering design skills. Our conclusion was that while the preservice teachers’ perception of self-efficacy in engineering design skills could be improved with the help of both digital and tangible materials, it was important to note that their self-efficacy with respect to technological pedagogical content knowledge needed to be bolstered with updated programs.</p>