## 5 Conclusions  
The conducted research focused on the calibration methodology of a 3D printer using the masked stereolithography (mSLA) method--specifically, the Anycubic M3 Premium 3D printer. The material used for 3D printing the test models was Anycubic ABS-Like Resin Pro 2.0. The study took into account factors affecting the quality of printed components, such as the uneven illumination of the LCD matrix and exposure time. Exposure time was linked to properties such as the ability to reproduce fine details, print strength, material shrinkage, and the extent of light bleed. The most important achievements and research results can be summarized as follows:  
1. The study involved calibrating the uniformity of UV intensity emitted by the LCD matrix of the Anycubic M3 Premium printer using a grayscale correction mask. Based on the nonlinear relationship between grayscale levels and UV intensity, a decision tree regression model was developed. This model enabled the generation of a brightness correction map. The application of this correction mask significantly improved the uniformity of UV radiation distribution across the matrix surface. 2. Models were developed to determine the optimal exposure time. Based on the analysis of the number of correctly printed pins and holes, the optimal exposure time was determined to be 3 s. A shorter exposure time resulted in incomplete resin curing and fewer printed pins, while a longer exposure time increased the light bleed effect, which degraded the quality of the holes. Optimization based on an objective function that maximized the number of both features allowed for a balanced compromise between the quality of the pins and the holes. 3. The study determined the linear shrinkage of samples based on the displacement of markers relative to their nominal positions, taking into account the sample type, exposure time, and distance from the center. The distance of the marker from the center of the sample had the greatest impact on shrinkage, with larger displacements observed for samples with a hole. Based on the analysis, shrinkage values were established at 0.36% for solid samples and 0.44% for samples with a hole. The adopted methodology enabled the determination of a scale correction factor. * The measurement error, reduced by the theoretical displacement that can be compensated through scaling (dl) and which is influenced, among other factors, by light bleed, was similar for the external dimensions of both solid and holed samples. This error depended on the dimension type and the interaction between exposure time and dimension. For the samples with a hole, the error was not symmetrical around zero, which means it could not be attributed solely to the light bleed effect. It was shown that the dimensional error is influenced by the interaction of geometry, material shrinkage, and light bleed. * It is recommended to perform linear dimensional error compensation in two stages--first, compensate for material shrinkage, and then determine the correction factor through an offset adjustment. An extension of the research related to improving the accuracy of 3D printed models could concern the reduction of the shrinkage and offset correction steps into a single stage. To measure the centers of the markers needed to determine shrinkage, it is worth testing an image acquisition system and using image analysis methods to determine the required coordinates. Using image analysis methods, the process will be automated and therefore faster. Using a cheaper tool than the coordinate vision system, the methodology presented could be applied to home conditions. Conceptualization, P.T., A.B., P.K. and M.C. ; methodology, P.T., A.B. and P.K. ; software, P.K. ; validation, P.T., A.B. and P.K. ; investigation, P.T., A.B., P.K. and M.C. ; writing--original draft preparation, P.T., A.B. and P.K. ; writing--review and editing, P.T., A.B. and P.K. All authors have read and agreed to the published version of the manuscript. This research received no external funding. Not applicable.