The use of simulators has been described in a variety of fields as a training tool to gain technical skills through repeating and rehearsing procedures in a safe environment. In cerebrovascular surgery, simulation of skull base approaches has been used for decades. The use of simulation in neurointervention to acquire and enhance skills before treating a patient is a newer concept, but its utilization has been limited due to the lack of good models and deficient haptics. The advent of 3D printing technology and the development of new training models has changed this landscape. The prevalence of aneurysms in the pediatric population is much lower than in adults, and concepts and tools sometimes have to be adapted from one population to another. Neuroendovascular rehearsal is a valid strategy for the treatment of complex aneurysms, especially for the pediatric population. The authors present the case of an 8-year-old boy with a fusiform intracranial aneurysm and documented progressive growth, who was successfully treated after the authors rehearsed the placement of a flow diverter using a patient-specific 3D-printed replicator system model.