Geometric Dimensioning and Tolerancing (GD&T) is an important tool for engineers to efficiently communicate design intent and requirements. GD&T has several advantages but can be difficult for students to learn due to the inherent 3D nature of the geometric tolerance zones. This paper describes an example of how 3D CAD models and 3D printed parts were used to illustrate several GD&T concepts including position tolerance zones, bonus tolerances, and designing functional gages for part inspection. The example described in this paper was implemented in a sophomore-level CAD course. The example was successfully delivered to a class of 45 students during the Fall 2017 semester. A description of the example is presented and, administering the example, requires simple 3D CAD modeling software and a 3D printer which are common in most engineering schools. Continuous improvements to the example are made based on faculty observations and assessments, as well as an end-of-semester survey administered to the students.