Post processing can be essential to certain 3D printed parts. Depending on the technology used, the goal of the project, and what materials were used in the printing of your object post processing can be crucial to the form, fit, or function of your object. For example:
–FDM printed models can require sanding, drilling gluing or painting just as you would with any other plastic part. Unlike SLS, SLA printed parts use support structures and require a bit more post processing. SLA models can be vapor honed, bead or sand blasted, or can be electroplated with metal. In plastic material jetting, layers cool or harden by UV light, and this type of post processing can also removes support material.
Check with the printer manufacturer for specifics.