The additive manufacturing technique is gaining importance as a fabrication method because of its multiple advantages including combination of materials and constituents that otherwise might not be possible by using traditional techniques. This fact leads to the fabrication of highly specific composites. Nevertheless, the elemental analysis of the materials tailored using additive manufacturing is difficult because of the differences among the constituents of the composite. In this work, we analyze the use of the energy dispersive spectrometry (EDS) as an analytical technique to study thin layers of additively manufactured materials. In this work, size-controlled layers of polylactic acid (PLA) were 3-D-printed on aluminum stubs and the signal of the characteristic X-Rays was analyzed at different conditions including time of exposure and electron beam experimental conditions to characterize the thickness, density and porosity of the layer. The electron-material interaction signal was simulated using CASINO^TM software to model and characterize these parameters. The overall energy dispersive spectrometry signal was analyzed to determine the elemental composition of the polylactic acid layer. The study of the EDS signal and the simulation of the electron-material interaction allows determining the inner porosity of the organic material and therefore, the real density of the printed layer. These combined results show the utility of energy dispersive spectroscopy as an analytical technique and also as a technique to determine bulk and surface characteristics of the sample such as porosity and density to characterize thin layers.