## 4 Conclusions  
On the basis of the experiments carried out, it can be stated that when using 3D prints in an environment with an increased concentration of moisture, it is advisable to perform some form of post-processing, as the positive effect of the post-processing adjustments on reducing the material's moisture absorption has been statistically proven. The tensile strength test and the indentation test statistically demonstrated a positive effect on the stability of the mechanical properties of the samples in the case of any post-processing technology. On the contrary, in the case of the bending test or impact strength tests, this positive effect was not proven. However, the reason here is the multiple cross-sections of the samples and the relatively short interval of 60 degradation cycles. However, the aim of the experiment was primarily to analyze the applied coatings and their effect on moisture absorption, for which 60 cycles were indicated as being quite sufficient. In the case of both types of standards, the negative effect of the moisture absorption was statistically proven, especially by the indentation test, as here the loading force acted on the sample from the side that was in contact with the printing pad. This procedure thus made it possible to verify the adhesion of the individual printing layers, while it was statistically proven that the most significant decrease in the adhesion of the printing layers occurs precisely in the case of the standards. The degradation of the standards due to moisture absorption was also statistically proven by the tensile strength test. Here, however, the difference between the state before degradation and after degradation was not statistically significant since, in this case, the loading force acted along the axis of the printing layers. According to the obtained results, heat treatment appears to be a universal post-processing technology, as this method statistically improves not only the mechanical properties of the part but also limits moisture absorption. In general, it can be stated that by implementing heat treatment, the annealed part achieves comparable mechanical properties after the degradation test to the standards before the degradation test. The advantage of annealing is also the fact that the surface of the component is not additionally contaminated by the coating, which is also very advantageous from the point of view of recycling at the end of the product's life cycle. Furthermore, from the point of view of the quality of the barrier protection provided and the simplicity of the application, it is recommended to treat the surface with a synthetic coating or epoxy resin. The reason is the statistically proven low rate of moisture absorption. However, these two technologies do not show very suitable mechanical properties compared with heat treatment. However, e.g., by applying epoxy resin certified for direct contact with food, the result is a product that is harmless to one's health. Through this technology, 3D-printed components are, therefore, in compliance with the relatively strict Regulation No. 10/2011 on plastic materials and articles intended for contact with food, which is valid within the European Economic Area. However, the goal of the presented experiment was to verify the possibilities of post-processing modifications intended for implementation on components used in the automotive industry (on the exterior of the car). For this reason, it appears to be the most suitable option to implement heat treatment (before assembly) or the application of a synthetic coating or standard epoxy resin (after assembly). The potential of the mentioned technologies also offers room for their mutual combination. This procedure would result in a part with improved mechanical properties (obtained by annealing), which would simultaneously be provided with a barrier preventing moisture absorption (obtained by coating).