To develop and validate a controlled patient-derived process for producing an in vitro, nonrigid model of aortic arch aneurysm.\ A three-dimensional magnetic resonance (MR) angiogram derived from a patient with an aortic arch aneurysm was segmented by using a homemade software package, meshed and converted to Standard Tessellation Language (STL) file format. The authors transferred this format to a stereolithography machine to produce a replica of the entire aorta, including the arch aneurysm and supraaortic arteries, by pouring silicone rubber.\ A sturdy, life-size, soft, transparent plastic cast, accurately reproducing both the internal and external anatomy of the aortic aneurysm, was produced in less than 1 week. Comparison between the STL file format of MR angiographic images of both the patient's aorta and model enabled validation of the reliability of the manufacturing process.\ The combination of easy segmentation and conversion to the STL file format with stereolithography techniques enabled a realistic, life-size, silicone vascular phantom to be created from a live patient imaging dataset.