The following aspects of a bento lunch box can be customized:

1. Size and Shape: Bento lunch boxes come in various sizes and shapes, and you can choose one that best suits your needs.

2. Compartments: Many bento boxes have multiple compartments or dividers, allowing you to separate different foods.

3. Material: Bento boxes can be made from various materials, including plastic, stainless steel, and bamboo. You can choose one that fits your preference and budget.

4. Design: Many bento boxes come in different designs, including cartoon characters, floral patterns, and geometric shapes.

5. Accessories: Some bento boxes come with accessories like utensils, napkins, and even ice packs to keep your food fresh.

6. Color: Bento boxes come in a range of colors, from bright and bold to more subdued and neutral tones. You can choose one that matches your personal style or taste.