These are the three main pieces for a liquid ring vacuum pump. I have to do some more refined models with dimensions of actual bearings. However the concept is here and I will make it completely functional as soon as my maker bot shows up.

Basically you bolt the lid on with the impeller inside the chamber. Fill the chamber about half way with water and as the impeller spins the water is flung out evenly around the chamber. Since the impeller is offset, the void space between the impeller blades and the water changes size as it goes around creating a pocket of compression at the top and suction at the bottom.

Note this is a concept mock up. I will refine it into something functional once my makerbot shows up.