Pieced this together today after thinking about it for a couple. Modeled it after some hand operated vacuum pumps that gold prospectors use to suck stuff out of cracks in rocks.
(The blurriness is my fault, the cropping is Photobucket's fault, sorry)
Thought it might help me keep my rice fresh longer
The design is a bit crude and I've already thought of several improvements, but it does work. Its basically two one-way valves with a hand operated piston. Used a piece of all-thread for the shaft with a modified test plug for the piston. The device that fits on the jar is from FoodSaver. They make a regular and wide-mouth version.
Tex