This study explored science, technology, engineering, and mathematics (STEM) education through a practice-based approach centered on the Japanese tradition of Sangaku dedication. As Japan is geographically close to Taiwan and a popular destination for Taiwanese tourists, Japanese culture—through movies, anime, and video games—is familiar to many young Taiwanese students. In Japan, “Ema” plaques, commonly used for prayers and blessings, are displayed in Japanese shrines, where visitors write their wishes on wooden plaques and hang them in the Ema gallery. Historically, Japanese shrines also held educational functions. Thus, mathematicians often wrote mathematical problems on wooden tablets and dedicated them to shrines for others to solve. This practice, known as “Dedication of Sangaku to the Gods,” traditionally incorporates three elements: gratitude for divine blessings, respect for mathematics teachers, and presentation of mathematical study results. On the basis of Japanese mathematical cultural artifacts, the researcher developed a Sangaku design teaching resource. The course was structured into two parts: thematic discussions and a practical activity integrating the history of mathematics with modern technology. Twenty-three students from an elective course on the history of mathematics participated in the study. The activity, titled “Laser Cutting of Sangaku,” provided the students with a hands-on STEM experience. An analysis of classroom practices, student questionnaires, and reflections indicated that this activity positively influenced the students’ mathematical thinking, cultural understanding of mathematics, and STEM learning experience. The findings highlight the potential for implementing STEM education using mathematical cultural themes such as Sangaku and also demonstrate the possibility of STEM courses focusing on the development of mathematical culture.