Fermi National lab operates and builds particle accelerators for research in nuclear and particle physics. Particle accelerators use electric fields to accelerate a beam of particles that is directed and focused by magnetic fields. The beam of particles travels unobstructed inside a vacuum until it reaches its target. Fermilab’s high energy particle accelerators require ultra-high vacuum environments, typically 10^-9 torr.  Achieving this level of vacuum requires the use of materials with low outgassing rates. Stainless steel is widely used for structural supports, piping, and vessels which are exposed to a vacuum. The vacuum properties of stainless steel are well known when fabricated using traditional methods such as machining, extrusion, and casting. However, such properties for 3D printed stainless steel are not as well known. The purpose of this study is to investigate the vacuum properties for stainless steel made by additive manufacturing direct metal laser sintering (DMLS) technology. Vacuum outgassing rate is measured for stainless steel reducers. By establishing the vacuum properties of 3D printed stainless steel, Fermilab engineers may have a new alternative fabrication technique in which to create complex parts that can be used in the vacuum environment for current and future accelerators such as LBNF and PIP-II.