Increasingly, the fabrication of steel components is being done via 3D metal printing. One of the most commonly utilized reliable and precise methods is called selective laser melting (SLM), and it involves the use of metallic powder as the material that is fed into the laser. One of the famous problems that SLM technicians face is the roughness of the printed parts. The goal of this paper is to study the effect of tumbling on the M300 maraging steel, which was produced by using a Renishaw AM500 3D SLM printer. An examination of a procedure that is both cost-effective and efficient for manufacturing and surface treatment is carried out within the scope of this research. The post-processing was investigated in depth, which resulted in 2D surface roughness Ra = 0.39 µm and 3D surface roughness Sa = 0.4 µm. The topography and morphology of the specimens were checked. Additionally, the surface wettability was tested, and it was seen to display wetting behavior, the improvement in surface wettability caused a better surface energy.