In recent decades, an increasing number of countries have integrated science, technology, engineering, and mathematics (STEM) into their curricula for early childhood education and care (ECEC). In contrast to this trend, many ECEC professionals are still reluctant about the idea of teaching STEM to young children. A reason for this might be too little experience with and knowledge about STEM. One way to tackle this problem is to address STEM in ECEC teacher education in a way that is engaging, motivating, and practical, and shows ECEC student teachers appropriate ideas for how to teach STEM in a playful and child-centred way. This case study aims to present and analyse an innovative approach to ECEC teacher training. We let the student teachers build their own automata (toys that have mechanical moving parts) to promote a better understanding of STEM. The students were highly motivated, assessed the approach as exciting and relevant, and consequently could successfully reflect on STEM content and pedagogy.