This paper reports on a mixed-methods, design-based study conducted with five classes of Primary 6 (age 11-12 years) students learning the properties of 3D solids. The researcher and participating teachers designed mathematics lessons that integrated the hands-on construction of artifacts (i.e., making) with a class set of 3D printing pens to introduce various properties of prisms and pyramids in two primary schools in Hong Kong. Quantitative results show that the designed learning activities with 3D printing technology greatly supported student learning on all questions related to working with vertices (0D), edges (1D), and faces (2D). Qualitatively, one researcher observed that the students produced hand movements and language that were conducive to learning the properties of 3D solids while they interacted with 3D printing pens. This study draws attention to the unity of mind-body and body-tool interactions in the act of making something (i.e., mathematics learning as embodied making).