3D printed models are often very similar in shape and can be inadvertently switched if the related patient is not identified correctly. Here, we present a free and simple method to imprint letters and numbers in a 3D model. CT scan data were used to create an STL file of a patient's mandible. We then used Blender software to modify it with numbers and letters. We chose to imprint a series of four letters and numbers on our 3D models. We chose representative letters and numbers of the Latin alphabet. Six models were printed with an Up plus 2 – easy 120 3D printer with different character sizes and shape to evaluate the readability. All models were printed without any failures. Regarding readability, 2 mistakes were made among ten readers. The favourite extrusion depth was 3 mm, and the largest model was preferred. Identification can be done at different times and by different means, but identifying the 3D model during its creation is safer. Moreover these identified 3D models could be saved in the digital patient medical file. The identification location should take into consideration the future indication of the 3D printed medical model. We recommend that 3D identification should be done using at least 7.5mm high, with a depth of 3mm. Our method allows easy, fast and free 3D text. This 3D text identification printing method may be a first step towards the legal use of 3D printed models made within the hospital.