More than 90% of atrial thrombi in patients with non-valvular atrial fibrillation originate in the Left Atrial Appendage (LAA), a diverticulum of the left atrium of the human heart, whose morphology predisposes the stasis of blood within it. The Left Atrial Appendage Occlusion procedure shows promise for reducing the risk of stroke due to blood clots in the body circulation after forming in the LAA; however, it must be performed by experienced operators due to the numerous associated risks. The objective is to develop a simulator for training novice operators in the procedure to plan the optimal occlusion path on representative models. Starting from a dataset of 20 diagnostic images provided by the Azienda Ospedaliero Universitaria of Careggi, a three-dimensional reconstruction of the anatomical areas involved in the surgical procedure and their spatial identification are performed. These results are used to design a device for the adjustment of a 3D printed model of the LAA with correct orientation and spatial coordinates. The simulator is a highly customizable and patient-specific prototype system; the ease of use and small size help its acceptability and reduce the time required for practice in use. The maximum positioning errors associated with the resolution of the measuring instrument is estimated at 5%; it is therefore considered acceptable.