There are two main drivers of whether or not a metal alloy is printed today: printability and demand. Though there are a wide variety of metal 3D printing processes out there, nearly all rely on metal powders. These materials take two forms in printing: raw 3D printing metal powders, or bound powder 3d printing metal filament. As a result, the metal materials printable today are to a large degree constrained by powder availability and whether or not that powder can be effectively bound. Aluminum, as an example, is notoriously difficult to print well and is as a result relatively uncommon.