The article describes each stage of the autocatalytic electroless metallization process of thermoplastic polymers produced with 3D printing technology. In particular, the influence of the preparation of the sample's surface layer on the quality of the finished metallic coating was assessed. Samples made of polylactide filament and polylactide with the addition of copper were subjected to metallization. In the metallization process, six different etching solutions were prepared to etch the polymer’s surface layer. The concentration of sulfuric acid VI was 200g/dm³ or 100g/dm³, sodium hydroxide 100g/dm³, and potassium permanganate 50g/dm³ or 20 g/dm³. The microscopic analysis and measurement of the arithmetic mean of the ordinates of the surface roughness profile of the samples for the selected process steps are presented.