Purpose This study aims to develop a realistic 3D printing-based simulator for the training and planning of the left atrial appendage occlusion (LAAO) to be used in the cath lab. Design/methodology/approach Starting from a pre-operative computed tomography dataset of a patient already treated with LAAO, the model was obtained, consisting in the right and left heart, opportunely assembled to replicate the position and orientation of the patient's anatomy while lying on the cath lab table. Different 3D printing techniques and materials were used to mimic the interaction between the cardiac tissue and the clinical instrumentation. The simulator was tested in the cath lab under proper image guidance by three LAAO expert operators. The clinicians were required to assign a score in terms of realism to each material used to fabricate the fossa ovalis and the LAA. Findings The simulated interventions were successfully performed by the operators, who were able to navigate in the system and release the occluder device as during a real procedure. The intraoperative images acquired during the simulations were highly comparable with data from a real intervention, with a mean percentage difference below 10%. Originality/value This study demonstrated the feasibility of the proposed simulator to faithfully replicate the LAAO procedure and its potentiality to be used for multiple purposes, including the training of the young clinicians, the evaluation of the most complicated cases and the design of novel occluder devices, in a fully realistic setting.