However, the ability to make almost anything is exactly what makes 3D-printing very controversial. With the ability to make almost anything, people can make blueprints for weapons, which could be posted on the internet and fall into the wrong hands.
Despite the fact that 3D-printing can be used for creating controversial things like weapons or weapon parts, it can also be used for medical purposes. Already prototypes for organs and body parts have been made. There have already been prints of hearts and fingers, using the patients cells. Unfortunately, the parts don't work just yet, but researchers plan on getting them to work in the near future.