Material extrusion (MEX) additive manufacturing has become, in recent years, one of the most accessible and widely used methods for producing polymer components, primarily due to its low cost and operational simplicity. Despite these clear advantages, achieving high-dimensional accuracy remains a critical requirement, particularly when parts are intended for technical or industrial applications where geometric deviations may affect assembly, functionality, or long-term reliability. In this context, the present study systematically examines the dimensional accuracy of polylactic acid parts fabricated via MEX, evaluating both internal cylindrical geometries (bores) and external ones. The investigation explores the influence of nominal diameter, spatial orientation on the build plate, filament color, and infill density on the measured dimensional deviations, aiming to identify the extent to which each parameter contributes to the occurrence of errors. The results indicate that accuracy is significantly affected by the type of cylindrical surface and the nominal size, with small-diameter bores exhibiting the highest percentage deviations. The findings provide a coherent basis for outlining future precision classes applicable to polymer components manufactured through material extrusion, while also contributing to improved predictability and process optimization during the design stages of additive manufacturing.