Liquid metal printing, developed by MIT researchers, rapidly creates 3D metal structures by depositing molten aluminum along into a bed filled with microscopic glass beads. The process can produce low-resolution objects like frames for chairs and tables in minutes.
In terms of speed, you’re totally right. That said, thete are tons of methods of turning a plastic 3D printed part into a metal part via sand casting that you can do at home. With enough money, evidently you can skip the plastic stage completely: https://www.exone.com/en-US/parts-and-services/sand