I am trying to get a full list of parts created that I will have to CAD up, and seeing examples of existing parts. The faucet is the only external part along with the button or handle that is currently visible in most designs from the outside so I am doing a quick search and seeing the tech drawings I can find. All parts in plumbing seem to be joined together with threads, so are screwed into place to make them water tight. These are all made from brass as this is the longest life.
There really isn’t anything that I could find that was multi-directional flow, going from upwards to downwards but I have only just started looking.
Elkay 3 this tech drawing is not so detailed, but has a good exploded view.