Re: question to those with dualmetal/trimetals
it's fairly modular. Each of the pieces seems to be made from a sheet that is usually formed intot eh needed shape and fitted from there. It involves a lathe and the proper tools. I forget the name of the actual process but it's basically stretching the metal and forming it into a bowl like shape. I am led to believe this because my double trimetal has no such seams other than on the hose port. I believe the stem is made in this way with an extruded pipe down the center and the heart is a solid cast piece of metal that is then adeed to with the ports and proper plates.