With the ongoing national focus on integrated STEM (science, technology, engineering, and math) education, middle school science teachers are incorporating new technologies and pedagogies into their classrooms. One relatively recent addition is 3-D printers and their associated computer-aided design (CAD) software, which are becoming more common in schools across the United States. In this article we provide teachers with six practical strategies for integrating 3-D design into the science classroom. We developed and tested these strategies through our combined 42 years of experience teaching 3-D design and printing at STARBASE Minnesota, a Department of Defense (DoD) program. If you have no experience with CAD, we recommend downloading a free CAD program and trying it! A variety of CAD programs are available to educators. PTC Creo provides a free student version of the professional software that is widely used throughout engineering industries (see Resources). SolidWorks is also widely used in engineering and offers a student version; however, after the free trial period, the software requires payment (see Resources). Tinker-CAD was designed for students and nonprofessionals and is free (see Resources). It is an easy-touse application and includes electronics and coding in addition to 3-D design capabilities. The more time you spend designing and tinkering, the more opportunities you will find to bring the technology into your classroom. To provide a useful context for applying the six strategies, we will discuss each strategy as it relates to a project in which students design and 3-D print prototype rocket fins. This project evolved from curricula originally developed for the STARBASE Minnesota summer program, with potential implications for the national Department of Defense (DoD) STARBASE program. Many talented STARBASE Minnesota instructors contributed to the project development and improved it through multiple teaching iterations. In this project students design rocket fins of varying shape and size. They then 3-D print their prototype fins, use them in a rocket launch, and evaluate their rocket performance to determine whether the independent variables of fin size and shape contribute to stable flight over long distances. The examples we share throughout this article use the PTC Creo CAD software. As previously mentioned, there is a free student version of the software, and it is an industry leader in digital solutions, including CAD.