COVID-19 PEEP one way adjustable valve 3D printable : this one way valve hepls keep Positive end-expiratory pressure in lungs for patient under assisted breathing, in case of lack of medicaly aproved PEEP valves can easily 3D printed without support , composed of 2 mandatory parts an one optional part (stl and step files ).
you will need a spring (i used the one under the bed of a 3d printer) and an M3 screw to adjust the presure, assembly is straight forward see images.