## 6 Conclusions  
Although we are aware of the fact that today there are several different techniques for protecting 3D models, the dominant being to create a watermark, we started with a dissimilar approach which is special/different in the sense that each cultural heritage object is seen as a unique object. We have created two 3D models of the sculpture; one is a 3D model of the original sculpture and the other is a 3D model of the sculpture with a built-in error. Both the original sculpture and the sculpture with added 3D segments were digitized by photogrammetry and a 3D scanner based on structured light. The main idea of our paper is to enable the visibility and artistic experience of sculptures and other artistic artifacts through online access to their 3D models with built-in protection. As these works have great artistic and material value, our approach in a new way enables the protection of the original 3D model from theft or misuse. Namely, we added material to the original model of the sculpture in a couple of places with the help of a sculptor, and then we digitized a sculpture \"with an error\" again. The error added in this way is discrete and will not diminish the artistic experience of the sculpture, that is, the average viewer will be convinced to observe the 3D model of the original sculpture. Our hypothesis that the 3D model of the original sculpture and the 3D model of the sculpture with the built-in error is the most visually similar was confirmed by a survey of 195 respondents. Only the 3D model of the sculpture with digital error will be exposed to the public, and the original 3D model will be archived. Although this approach requires an individual observation of each work of art, it also offers some advantages. Digitization and protection of models, in this way, can be done by employees in cultural institutions and this approach, where artists are included, is acceptable for experts in the field of art and culture, who do not have adequate knowledge of programming and algorithms, and such knowledge is required when creating a watermark. We believe that this approach can enable mass digitization of works of art, their visibility through 3D models with digital error, and again protection against theft and misuse. Unlike most works in which the watermark 3D model is added using different mathematical approaches and algorithms, this individual approach to each artistic 3D work can be considered a good solution that enables the presentation of cultural heritage but also preserves it from abuse. The disadvantage of the approach is that each work, i.e., 3D model, requires an individual approach and cooperation of artists and technical staff. Another disadvantage may be that the clay that we applied needs to be removed from the sculpture after shooting. Some materials from which sculptures are made, such as marble, steel, or bronze, can be easily cleaned off the applied clay without damage. Gypsum sculptures, on the other hand, are susceptible to damage during clay removal. Therefore, future research could examine the application of a haptic hand that can be used for digital sculpting. In the haptic hand, the sculptor has realistic resistance in the glove, and this procedure is the most approximate simulation of real sculpting. In digital sculpture, the starting model is a 3D model obtained by digitizing the original sculpture. We noticed three shortcomings in our procedure. The first is that it is necessary to use the assistance of a sculptor to work with each individual sculpture. Another disadvantage is that, when applying clay to the sculpture, contact is made with the sculpture, and after the digitization of the altered sculpture, it is necessary to remove the added material. During this process of removing the material, the sculpture can be damaged. According to the experience of sculptors from our team, there are clays that are easy to apply but also easy to remove, so it is possible to apply such clay and remove it without damaging the object.