This picture shows the seal of a custom fit aircrew oxygen mask, fabricated by FDM using 72 Shore A thermoplastic elastomers.
The elastomeric part was built using 0.010" (0.25 mm) slices, 0.012" (0.30 mm) wide roads, 0.8"/s (20 mm/s) head motion, and a 0.012" (0.30 mm) extrusion die. The transparent nature of the build material makes the part surfaces seem rougher than what they actually are. The horizontal line through the part is due to a material loading problem that lasted while fabricating those two layers.