A living hinge is highly dependent on the injection molding process, and one cannot create a "proper" living hinge with a 3D printer. The whole point of a living hinge is to force the material through a very thin area of the die, which lines up the polymer structure to a consistent orientation perpendicular to the hinge joint.

Without this structure, the polymer chains will not extend across the joint and will eventually separate, breaking the hinge. With proper polymer chain orientation a living hinge can last tens of millions of cycles. Without, it might last just ten.

All that being said, if you can print the hinge correctly (orientation of the strands perpendicular to the hinge axis), and you use the correct material, AND you keep the thickness to a proper level (I would say no more than .20 at most), you can get a functional part. It won't last as long as an injection molded hinge, but should get you by for prototypes.

http://www.caddedge.com/stratasys/3d...nge-protoytpes

This seems to be a good read on the subject, but even that link basically states that around a hundred cycles is a good upper limit to expect.

A bulky, thick joint with a secondary flexible material is not something that we recommend for most applications in the injection molding industry, though it does have it's place.