In this work we present a design procedure of acoustic metastructures for noise reduction. These metastructures consist of an isotropic solid matrix containing cavities or inclusions that modify the propagation of elastic waves in the medium. By adjusting the position and geometry of the inserted inclusions it is possible to minimize the amplitude of the waves. A previous numerical analysis was carried out to observe the amplitude distribution of the wave displacement using the boundary element method. The designed metastructure was developed based on previous numerical simulations. The designs obtained were manufactured using a Creality Ender-7 3D printer using a polylactic acid (PLA) filament. The sound absorption coefficient and sound reduction index were determined in an impedance tube following ISO 10534-1:2001. The 3D printed metamaterial designed confirms the possibility of making acoustic metamaterials that can be made more efficient by adjusting their absorption spectrum to the customer’s needs. This may enable a significant development of a wide range of new and diverse designs in acoustic technology with excellent perspectives.