Comfortable Head Strap for reusable respirators and medical masks

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Fortunately, this issue has been resolved by 3M several decades ago with their 6200 series respirators, and their patents on the design have expired. We have reverse engineered the design for 3D printing. To fit the print on a 200mm build plate, we broke down the strap into two parts that snap together. It is less than 1mm thick, and it can be printed in rigid material like PLA without support. If stringing interferes with the buckle insertion, it can be easily cleared out with a small screwdriver. To further optimize mask support, we recommend using 1/2 inch elastic and crisscrossing the straps such that the printed part (which sits on the crown of the head) attaches near the chin of the mask, and the strap around the back of the neck attaches near the nose of the mask. This results in a minimum force requirement from the elastics as the force vectors will be applied normal to the chin and nose surfaces for optimal sealing against the face. Progress on the design can be tracked at https://bemask.org/.