We 3D print metal hips, knees and spine parts so far. We are planning no 3D printing in metal for other parts of the body.
How? We use software to draw the part we want to make in 3D. We use more software to slice the model into layers. In the metal 3D printers, we lay down metal powder and then melt selectively, wherever the model directs for the first slice. Then lay down another layer of powder, melt the next slice and so on until we have melted each slice. The part build is in a bed of unmelted powder, which is easily removed. Then you’ve got your 3D printed part.