It is common for airfoils to come to an infinite point at the trailing edge (also seen in many other places). Figure 1 - Edges, shows an infinite edge and what it will cause the printer to do.
Figure 1 : Infinite edge produces uneven finish
When making an airfoil, or any other surface that comes to an infinitely small point, it is important to flatten the edge so that there is a .02 in (0.5 mm) wide edge. All CAD programs have a sweep option where a cut profile is made and a trajectory line (the infinite edge) is chosen to cut off the infinite point. This technique applies to all geometries (ex: swept wings). See figure 2 for an example.
Figure 2: Trimmed Trailing edge