Access to maker technologies has catalyzed and amplified the possibilities for creating physical materials that are responsive to the needs of students. Opportunities for design and fabrication of original mathematics manipulatives have been incorporated into the teacher education program at Montclair State University. Participating preservice elementary teachers design and make original mathematics manipulatives. Three case studies examine ways in which this process enhances students' mathematical reasoning, sense-making, and understanding. The designs created are made available through links to the open source Educational CAD Model Repository, enabling others to replicate the objects described.