This hands-on introductory course introduces students to the fundamentals of 3D modeling and design using industry-relevant software tools: Tinkercad and Onshape. Students will explore the principles of computer-aided design (CAD) while developing the skills to create, modify, and visualize 3D objects in both beginner-friendly and professional-grade environments. The course begins with Tinkercad, where students will learn the basics of 3D geometry, object manipulation, and simple prototyping through intuitive drag-and-drop modeling. As students gain confidence, they will transition to Onshape, a cloud-based CAD platform used in professional engineering and design workflows. Here, students will explore parametric modeling, sketching, assemblies, and collaborative design practices. By the end of the course, students will have created a portfolio of 3D models, understand the design process from concept to prototype, and be prepared to bring their ideas to life with 3D printing or further engineering education.