Backpacks having lumbar pads as at least one component that has been manufactured using 3D printing or other additive manufacturing technologies. backpack may include 3D manufactured parts including a lumbar pad, shoulder harness, hip belt, or back panel. The component or lumbar pad may include a lattice structure that allows airflow or provides cushioning. The lattice structure may: have multiple layers, include a network of beams and nodes (e.g., that create cells), or be monolithic. The cells may be polygons (e.g., hexagonal) or cells may line up in multiple layers of lattice structure. Cells that line up may have equal numbers of sides. Other embodiments include systems for providing custom backpacks where consumers enter consumer body dimension(s) and the system fabricates a custom backpack or component using the body dimension or desired load capacity, for example, using 3D printing.

A bag with adjustable firmness and a using method thereof, which relate to the field of travel goods. The bag includes a bag body and an inflatable airbag. An airbag accommodating space is arranged around an inner side of the bag body. The inflatable airbags are arranged in the airbag accommodating space and around the inner side of the bag body in a circle with space between each other. Inflation of the airbag increases the firmness of bag panel to achieve structured and three-dimensional shape for the bag body. Deflation of the bag decreases the firmness of bag panel to allow bag body to be softer and easier to store. The expansion or contraction of airbag can adjust the firmness of bag body according to actual usage scenarios, solving the problem in conventional bags where flexibility and rigidity of fabric cannot be adjusted to suit different usage needs.