To provide simple yet accurate stent graft fenestration, a patient-specific fenestration template is used as a guide for graft fenestration. To generate the fenestration template, a patient's medical imaging data such as CT scan data may be used to generate a 3-D digital model of an aorta lumen of the patient. The aorta lumen may encompass one or more branch vessels, which may be indicated on the 3-D digital model. Based on the 3-D digital model or a segment thereof, the fenestration template may be generated, for example, using 3-D printing technology. The fenestration template may include one or more holes or openings that correspond to the one or more branch vessels. To fenestrate a stent graft, the fenestration template is coupled to the stent graft so that the holes or openings on the fenestration template indicate the fenestration locations.