Additive manufacturing refers to the group of new manufacturing methods where parts are built layer upon layer starting from a digital file. Using these new manufacturing technologies is possible to produce parts with an incomparable design freedom with theoretically any material. The quality of the built products depends mainly on the machine capabilities the quality and the type the metal powder used for the building process and the choice of the process parameters. The paper presented aims to study the origin of defects that appear on the polished surface of the metal additive manufactured parts with selective laser melting in maraging steel grade 300 and how they can be reduced. The main purpose is to understand how these defects can influence the quality of the injection moulded products when additive manufacturing is used to produce moulds that would present the defects under analysis.