Instead of making the can/container, why not use one of the metal water bottles that seem to be popular now? They are one piece, so there would be no problems with leaks. And steal the plans for the pump from an existing oil can, but use better materials with closer tolerances. This could be a fun project and wouldn't be the first time I've spent $20 dollars on stock and several hundred dollars of time to make a $10 item. That's why it's a hobby.
Glenn
Glenn