Oh, almost forgot...
Brad :
The top actually could be 2 pieces, one the larger flat piece and the other the smaller piece with the o-ring groove around it. They shouldn't even need to be soldered together since the pressure seal is created on the side face, meaning no water would reach the interface between the two lid pieces. For just about totally fail safe protection, you could even put a groove in the bottom of the top plate that was centered on the the edge of the bottom lid piece and end up with a double seal
