I'm working on an invention which requires that I increase the internal air pressure of a container (while keeping it simple and cost-effective to produce). I know my 3 options are to either: introduce more air into the container, increase the temperature, or decrease the volume. One idea I had is trying to figure out a mechanism where the end user could simply press down on a lever, which would act similarly to a french-press (though the area being compressed would be air tight). There would be a ratchet to keep the lever from popping back up again due to pressure. Not sure if this would be the best approach. Any ideas or suggestions on how to best tackle this problem?