The study of chemistry, particularly at the molecular level, presents considerable challenges for students due to the highly abstract nature of molecular structures. Three-dimensional representations are essential for comprehending molecular geometry, bonding, and polarity. This study introduces the Multimolecular Structural Sphere (MMSS), a 3D-printed, didactic tool designed to enhance conceptual understanding of molecular geometry through tangible, student-centered learning. The project was implemented in the course Foundation of the Structure and Transformation of Matter at Tecnológico de Monterrey, campus Puebla, México (August-November 2024). Two groups were compared: a traditional instruction group (n = 52) and a treatment group using MMSS (n=64). Although no statistically significant difference in average grades was found (6.9 vs. 7.0), the MMSS group demonstrated greater dispersion of scores, with a subset of students scoring below the mean, influencing the overall result. Exploratory and Confirmatory Factor Analyses (EFA and CFA) of the knowledge survey provided evidence of construct validity, supporting a refined 15-item instrument structured around three thematic dimensions of molecular geometry. Student perception results were notably positive, 83% found MMSS highly beneficial for learning and 86% reported increased motivation to study chemistry (n=62). The MMSS proved to be cost-effective, durable, and easily reproducible through 3D printing, offering broad potential for adoption in educational contexts. Entering the second phase of this project-focused on refining the model, enhancing the survey, and strengthening its pedagogical integration, the findings suggest that the MMSS can transform the teaching of complex chemistry concepts, making them more intuitive, engaging, and accessible for students.
