Microscopic features of human anatomy, like alveoli and villi, are challenging for young learners to engage with. Their visualization tools - microscopes - are not powerful enough to view these tiny structures directly, and 2D images in textbooks or online cannot convey the details of these structures. In this 7th grade class, students created their own 3D models of these interfaces between body systems to show features like immense surface area and the proximity of circulatory system capillaries that supports diffusion from one system to another.