Living hinges are normally very difficult to design and 3D print, since the plastic will break very easily if not modeled properly. We have designed a few different version of this 3D printed living hinge with much success, having the parts bent hundreds of times without breaking.
These parts are printed in PETG or PET+ since we found this material to work best with this application. The various blends of PET provide additional elongation to break over ABS and PLA. This reduces the wear on the 3D printed living hinge as it is cycled over time.