A three-dimensional (3D) printer includes an ejector having a nozzle. The 3D printer also includes a heating element configured to heat a solid metal in the ejector, thereby causing the solid metal to change to a liquid metal within the ejector. The 3D printer also includes a coil wrapped at least partially around the ejector. The 3D printer also includes a power source configured to supply one or more pulses of power to the coil, which cause one or more drops of the liquid metal to be jetted out of the nozzle. The 3D printer also includes a substrate configured to support the one or more drops as the one or more drops solidify to form a 3D object. The 3D printer also includes a gas source configured to cause an oxygen concentration to be less than about 5% proximate to the one or more drops, the 3D object, or both.