We explored if it is possible to print one-way valves. Two prototypes were printed and both works surprisingly well. Although some air is still leaking out (because of the cleaning process to remove support material as it damaged the enclosed parts), it demonstrates that functional parts can be printed quite easily.
Below you can see the cross-section of both valve designs. The blue parts are the enclosed and can move around. The reds parts are seals made from softer material so the moving part can fully close one direction if pressure is applied from one side.