Aluminum alloy (AlSi10Mg) is a strong, low-weight material with good thermal properties. It is printed by sintering aluminum powder together with a laser to produce metal parts that are equally as good as machined models. 3D printed aluminum does not look like traditional shiny milled aluminum. Instead, it has a matte gray finish with a slightly rougher and less defined surface. The subtle sparkle you will notice is caused by the presence of silicon in the alloy.