Printing electronics is not new; screen printing, lithography, inkjet and other processes have long been used to manufacture circuit boards and components.
Optomec's Aerosol Jet works very differently from inkjet printing, in which a print head positioned barely a millimetre away deposits a droplet of ink on a flat surface.
Think about inkjet printing where you lay down ink on a page to make letters, and then do that over and over again to build up a three-dimensional object.