An apparatus and method for removing support material from and/or smoothing surfaces of an additively manufactured part (the “AM part”) is disclosed. The apparatus may include a chamber, a support surface within the chamber, and one or more nozzles within the chamber. The nozzles may be the same size or different sizes. The support surface may be configured to support the AM part. The support surface may have one or more openings sized and configured to allow the fluid to pass through the opening(s). The nozzles may be configured to spray a fluid at the AM part, and the spray may be an atomized or semi-atomized spray of the fluid. For removing support material from parts with internal spaces, such as cavities or passages, the apparatus can include a nozzle at the end of an adjustable flexible hose member that can be adjusted to spray into an internal space of the part. Alternatively, for removing unwanted support material from multiple parts with internal spaces, the apparatus may include a submersion tank.