So I'm trying my hand at engineering, and I thought "maybe an air conditioner would be a good place to start, that doesn't sound too hard". Stupid idea. Of course it's too hard. But I'm going to try anyways. So what do you guys think about this as a pump? I want to find a very clean cut, circular metal tube. inside the tube i want to wedge a circular rubber block of undecided depth. Then i want to screw through the rubber block, have a large (almost the size of the tube itself) washer tightened down on each side of the block, and the screw itself will be attached at the other end to the mechanism I have set up to push up and down. Is this realistic? Or am i going to see technical difficulties from such a set up?