After deciding on a vtail configuration, the design process began. My main tail section design considerations were strength and aesthetics. I started with a simple shape, the arms at 90 degrees from each other, a central support fin, and braces from the support fion to the arms. Once the simple shape was more or less what I wanted, I extruded it to the extent of my print bed capacity, about 150mm. I then created a large cylinder shape (all design work was done in SketchUp) and laid it perpendicular to the extrusion and chopped it out. Details were created in much the same way.
The bolt pattern for the motor attachment points was lifted from another model and plunked into this one. Once I had the details and functional bits done, I had to size it to fit my print bed. I chopped the arms off, making them fit over a stub on the main tail piece. Printing the main tail section took about 14 hours. The arms were only about 2.5 hours.