In STEAM education, 3D printing can be valuable especially for creating custom teaching material. Moreover, it can be used to create tangible visualisations of virtual concepts as are used in mathematics. As a motivational and learning bonus, it utilizes concepts of constructivism. However, learning to search for, create, and finally produce 3D models can be challenging for teachers. To help them, we developed a workshop introducing 3D printing in ten schools to around 200 teachers. In this workshop, we used the artwork we found in schools to support teachers in learning to create customized 3D printable cookie cutters. We experienced a motivational boost leading to more engagement, longer workshops, and a better understanding by teachers of how to create and print 3D models.