The Jet Fusion 3D printer takes a digital file and prints it as a three-dimensional object.  You start by taking a digital model and download it into the 3D printer. Then it melts plastic and then releases it into the form of a the 3D model.

https://www.computerworld.com/article/3071035/emerging-technology/hp-begins-selling-its-jet-fusion-3d-printer-says-its-50-cheaper-10x-faster-than-others.html

The Jet Fusion 3D printer, produced by HP, is a entirely new design. This design prints the plastic on to the work surface, then as it adds more layers it also adds a bonding agent to the plastic so they bond together. It also applies a detailing agent so the edges are smooth and the object is detailed.

http://www8.hp.com/us/en/printers/3d-printers.html?jumpid=ps_fhs8y4k25m&gclid=CMmJpPf229YCFYKYswodtXAErw&gclsrc=ds

Source: https://www.computerworld.com/article/3071035/emerging-technology/hp-begins-selling-its-jet-fusion-3d-printer-says-its-50-cheaper-10x-faster-than-others.html

This relates to engineering because it uses complicated electrical and mechanical engineering to make it work. It also uses thermal engineering to print the object. and chemical engineering to bond the plastics.