In digital fabrication, machine toolpaths specify how a machine translates a digital design into a material outcome. Material-focused approaches design directly at the toolpath level to create unique patterns, such as weaving effects in clay 3D printing. Visualizing toolpaths in AR can help practitioners gauge, interpret, and plan machine behavior. To better understand the potential of AR to aid the understanding of machine toolpaths, we present a user study involving nine 3D printing practitioners with varying backgrounds. We investigate the effectiveness of two AR modalities—head-worn (Hololens) and hand-held (iPad)—in visualizing machine toolpaths to improve the design process for clay 3D printing, and compare with the baseline workflow of desktop-only visualization. Findings indicate that Hololens and iPad modalities enhance contextual visualization and aid in understanding machine toolpaths, contingent on factors such as comfort, display characteristics, and integration to existing workflows. This study highlights the potential of AR for optimizing clay 3D printing design workflows and informs the development of tailored AR tools for enhanced user experience.