A tubular, folding flow diverter is provided. The flow diverter includes a plurality of sections, including a first section, a second section, and a third section. The flow diverter is shapeable to an elongated cylindrical shape and is movable to an implanted configuration. In the implanted configuration, the second section and at least a portion of the first and third sections overlap to form a three-layer shape. This three-layer shape can be positioned proximate an aneurysm neck when implanted in a patient. The overall porosity of the implant can be higher than legacy implants, because the overlapping portion of the three sections can decrease the porosity proximate the aneurysm neck.