When sourcing metal grinders, the material is the most critical factor for longevity and user safety. Aircraft-grade Aluminum (6061-T6) is the industry standard due to its high strength-to-weight ratio and resistance to corrosion. For premium markets, Stainless Steel is the superior choice as it is medical-grade, non-reactive, and virtually indestructible, though it comes at a higher price point. Avoid 'Zinc Alloy' for high-end retail, as it can be more brittle and may flake over time. Ensure the supplier uses CNC (Computer Numerical Control) machining rather than casting to guarantee precise threading and sharp teeth.