The additive manufacturing (3D printing) process of plates closely resembles the production of laminated composites. Both structures can be treated as multi-layered composites, where each layer may have distinct mechanical properties while forming an integrated structure. This study employs a non-destructive inverse technique based on dynamic tests to characterize the engineering constants (elastic parameters) of an individual printed layer. By using non-invasive experimental vibration tests (optical sensing), numerical modelling, and direct optimization processes, the engineering constants (elastic parameters) of an individual printed layer of a 3D-printed plate are identified. The results are validated by predicting and measuring the dynamic response of a different plate with a new stacking sequence. The findings demonstrate that Classical Laminated Plate Theory (CLPT) can predict the linear dynamic response of 3D-printed plates. The inverse technique is shown to be a robust and reliable method for determining the engineering constants of individual layers in a 3D-printed plate.