## 3 Results and Discussion
### Results of Measuring the Accuracy of Dimensions and Shape of the Manufactured Models
The results of the measurements showed that openings made with a 50% fill rate (the opposite of what was the case for cylindrical protrusions) are characterized by larger dimensional deviations relative to samples made with the same layer height but a different fill rate. However, in the case of the angular deviation of the opening's axis, the same samples were characterized by the relatively most accurate representation of the right angle in relation to the reference plane. In addition, an upward trend in dimensional deviation can be observed with increasing material layer height. Figure 13 graphically presents another set of features measured as part of the assessment of the dimensional and shape accuracy of the reference component. The surface of the model, highlighted in red, was used to determine the reference plane in measuring the perpendicularity of the protrusions and niches walls (highlighted in blue in Figure 13). The walls of the perpendicular protrusions and niches were measured relative to each other to determine the deviation in length and width of these geometric features of the samples. The measurement, as in the case of cylindrical features, was completed by contact measurement  
Figure 12: Charts showing the obtained measurement results: (**a**) average deviation of the dimension of the inner diameter of the cylindrical openings from the nominal diameter; (**b**) average deviation of the perpendicular angle of the cylindrical openings axes relative to the reference plane. at different heights of the walls, which made it possible to determine the distance between the planes of the protrusions and niches. Figure 14 presents a chart of length and width deviation of perpendicular protrusions for the nine samples measured. The measured values of the length and width deviations of the perpendicular protrusions indicate that the accuracy of the CAD model geometry reproduction in the FFF additive manufacturing process decreases with increasing layer height. In addition, samples with a fill rate of 50% have smaller values of dimensional deviations compared to samples with the same layer height but a different percentage of material filling. Most of the dimension deviation values are below the nominal dimension, which is due to thermal shrinkage of the filament material. Figure 15 presents a chart of length and width deviation of perpendicular niches for the nine samples measured. Figure 14: Average values of length and width deviation of perpendicular protrusions for the nine samples measured. Figure 13: Measured geometric features marked on the isometric view of the 3D CAD model of the reference component: the red color indicates the reference plane against which the perpendicularity of the geometries marked in blue was measured. As in the case of protrusions, niches are characterized by deteriorating geometric feature reproduction with increasing layer height. For example, for a fill rate of 70%, the niche length increases from 0.051 mm, with a layer height of 0.12 mm, to 0.228 mm for a layer height of 0.20 mm. For width, the deviation values range from \(-0.068\) mm to 0.016 mm. This indicates the need to consider the thermal shrinkage of the filament material.