Cylindrical designs reduce material consumption by approximately 10% compared to cubes for the same volume. The rounded sides prevent the tendency of spheres to roll, while the flat top and bottom ensure stability. Furthermore, common plastic water bottles (such as mineral water bottles) often feature grooves in their bodies. These grooves act as reinforcing rings, using a grooving method to transform the unstable sheet material into a reinforcing component similar to angle iron, thereby enhancing the bottle's stability under external pressure and reducing material usage.

Common plastic materials can be categorized based on the triangular recycling symbol at the bottom: #1 PET (Polyethylene terephthalate), commonly found in mineral water and beverage bottles, not heat-resistant (usually not exceeding 70℃), not recommended for reuse or storing excessively hot liquids; #2 HDPE (High-density polyethylene), such as laundry detergent bottles; #3 PVC (Polyvinyl chloride); #4 LDPE (Low-density polyethylene), such as cling film; #5 PP (Polypropylene), food-grade, microwave-safe; #6 PS (Polystyrene); #7 OTHER (Other), including PC (Polycarbonate) and Tritan (Copolyester), etc. #5 PP is the only food-grade plastic that can be microwaved. Among #7 plastics, Tritan (also #7) is resistant to high and low temperatures, BPA-free, and impact-resistant, commonly used in sports water bottles. PPSU (Polyphenylsulfone) is a high-performance plastic with excellent heat resistance (up to 220℃).

Stainless steel (such as 304 and 316 food-grade) is safe, durable, and has good thermal conductivity, making it commonly used in insulated cups. Stainless steel products (such as vacuum-insulated mugs) achieve dual-effect insulation for both hot and cold temperatures through a double-layer structure; laboratory tests show that it can keep drinks cold for up to 24 hours. Glass (such as borosilicate glass) is safe, resistant to both hot and cold temperatures, and its double-layer design provides insulation and prevents burns. Aluminum water bottles are lightweight but prone to heat conduction and impacts, and excessive aluminum intake is harmful; they usually have an internal coating.

The manufacturing process of water bottles varies depending on the material. Plastic bottles are typically made using blow molding, extrusion blow molding, or injection molding. The manufacturing of the inner liner, the core component of a thermos (hot water bottle), is more complex, mainly involving steps such as preform preparation, liner synthesis, silver plating, and vacuuming. Vacuuming and sealing the tail tube are crucial for forming the vacuum insulation layer.