3D printing with metal: The final frontier of additive manufacturing
When Humphry Davy first discovered the electric arc in 1800, he chose to call it an arc since the evaporating gases buoyed it up into an erratic but generally rounded shape. It was not until the advent of electron beams and vacuum chambers that precise metal printing would first be made possible.
The real breakthrough that has enabled 3D printing for the masses has been the laser. Spray welding is a technique that has been used for decades to build up worn motor shafts, but it is far too crude for controlled additive printing
Full Story: ExtremeTech