This part is a hydraulic piston used in a suspension system. It has seals that fit over the top and bottom surfaces and controls the damping in either direction of the wheel movement.
These parts would normally be made in high volume so you might plan to cast them and then post machine the mating surfaces. But flow through a viscous damper is highly non-linear and difficult to accurately model with CFD software. With 3D printing, you can print various geometries and get the performance just right before locking down the design.
Once the optimal design has been identified, you are ready to invest in cast tooling and ramp up to high volume production.