Anyway, here are some photos of the results. I ordered a dozen just to see how they would turn out. I am quite pleased with their shape. I plan to paint them to seal the material and put them in my details bin until I need them for a future layout.
Here is a comparison of the new 3D printed propane tank and my original scratch built tank behind it, created from a 1/4" wooden dowel, rounded on the ends, with a piece of sprue added for the dome.