Teachers can build their own AI tools using open-source resources, reclaiming professional agency while achieving pedagogical goals sustainably and affordably.

The dominance of commercial AI in education has created a paradox: while these tools promise transformation, they perpetuate dependency, financial barriers, and environmental unsustainability. This Element challenges the 'technical mystique', the misconception that AI development requires expertise beyond educators' reach, and demonstrates how teachers can become creators rather than consumers of educational technology. The authors chronicle their transformation from linguists and educators to AI developers without formal computer science training, illustrating how the technical barriers educators face are often more perceived than real. Through detailed case studies, including an AI-assisted Dialogue System (ADS) for multilingual nurse-patient training and assessment, they demonstrate how teachers can leverage AI coding assistants, browser-based models, and open-source resources to develop pedagogically tailored applications. This title is also available as open access on Cambridge Core.