Hello Heinrich, chemical vapor smoothing is a solid choice—it involves exposing the print to a solvent vapor that lightly melts the surface, smoothing out those layer lines and boosting the look. This technique works really well for ABS and certain types of PLA.

Dear Heinrich, vapor smoothing for FDM 3D prints is indeed good for smoothing out layer lines. You may just want to keep in mind that it will also affect the dimensional accuracy of the part quite a bit, because the process dissolves the outer shell of your print. There are various grades of vapor smoothing, and in the highest grade, the process will dissolve details and sharp edges.

If you need a preliminary finish to smoothen the surface before painting for instance, then sanding with grit sandpaper (150, 220, 400) is an option. Please note that it is not suitable for intricate surfaces and small details.

And finally, you can also apply an epoxy coating – it is suitable for all FDM thermoplastics. It smooths out any remaining imperfections and also adds a layer of resin to the printed part that fills the gaps.