For long-term storage, rigid polypropylene (PP), PETG, ABS plastic, and reinforced cardboard are the most popular materials. These are acid-free and PVC-free, ensuring no chemical reaction that could damage cards. EVA hard cases are widely used for portability and impact resistance, while acrylic cases provide display-level clarity. For distributors, offering a mix of durable and premium materials ensures appeal across casual, professional, and collector markets, maximizing wholesale sales opportunities.