Dishing Machines - forming metal plate into bowl shap

Starting with a flat sheet of steel this machine makes it into a bowl shape.   There are companies that do "aluminum fabrication services" that would have such machines and could make two halves of my float shape out of aluminum.  Also companies forming plate for ships.   Aluminum is softer than steel and so should be even easier to form.  So 8 of these and some welding and I could have 4 floats for a larger size quadmaran in the future.

There are also Phanishing hammers that are like small rapid dishing presses.  Since aluminum is softer these may work for thick enough size to be interesting, at least for small ones like the red plastic ones we have.

There are general aluminum robot welders:

Here is a page that talks about going from plate to nice dish ends.