It is being intensively used currently in lots of fields particularly in medical where you can create an artificial limb that fits you perfectly.

McDonalds is toy-ing with the idea of using 3D printing to let kids choose and create their own toy,

making processes finish faster

company has the design they can just make the prototype on their own.

Aside from the longer time spent in manual work, injury is also a big possibility especially to the person making the prototype.