The liquid metal turns to steam, flocculating the center as the steam rolls around, making the metal roll around in the dynamo shape.
Using layers of energy as the Earths crust does to keep heat in and reach temperatures you could not in open space without being layered our countries should be able to help metal reach its evaporation point artificially.
Metal layering in an artificial dynamo will keep heat in more efficiently then Earth can with just dirt and pockets of ore around. Then each layer can be heated to before its melting point and before it starts to warp, creating a blanketing effect around the metal in the center you want melted and evaporated. This version would need to entrance to the center once the dynamo is constructed, just sensors to keep the correct metals at the correct temperatures. Advanced versions can open, pulling in more energy while keeping their layers intact, as if Earth had a hole in it where extra energy was pumped into the dynamo.