**4. Conclusions**

In this work, six different post-processing techniques for fused filament fabricated Ultem parts have been proposed, and their effect on dimensional accuracy, mass, and surface roughness of the treated parts, compared. Microscope imaging has provided insight into the reasons behind the observed changes in surface roughness. From the obtained results, the following conclusions can be extracted:


Future works should focus on studying the affectation of the proposed finishing techniques on Ultem's mechanical performance and searching mathematical coefficients to predict dimensional and roughness changes.

**Author Contributions:** Conceptualization, G.G.-G. and M.A.P.; methodology, A.C.d.B.; validation, A.C.d.B.; formal analysis, G.G.-G.; investigation, A.C.d.B., G.G.-G. and M.A.P.; writing—original draft preparation, A.C.d.B.; writing—review and editing, G.G.-G. and M.A.P.; supervision, G.G.-G. and M.A.P.; funding acquisition, M.A.P. All authors have read and agreed to the published version of the manuscript.

**Funding:** This work has been supported by the Ministry of Science, Innovation and Universities through the project New Developments in Lightweight Composite Sandwich Panels with 3D Printed Cores (3DPC)-RTI2018-099754-A-I00; and by the RIS3CAT Llavor 3D Community co-financed by the Generalitat de Catalunya (ACCIÓ) through the project TRANS- PORT COMRDI16-1-0010 (2017–2020).

**Institutional Review Board Statement:** Not applicable.

**Informed Consent Statement:** Not applicable.

**Conflicts of Interest:** The authors declare no conflict of interest.
