I’ve been criticized for building the front fairing first, and holding off on the rear pannier/Tailbox for later. Actually the front fairing gives me protection so it’s more important. But the rear can carry more weight, and will mount on a standard commercially available rear rack, so I figured it would be easy . This larger Tailbox also has an 11° taper for aerodynamic reasons.
This is the pattern for the Coroplast. I can cut two of these from one 48” by 96” board, with the front and rear panels being cut from another board. It worked out that way this time, although there is another pannier design cut from one board in one piece (not always possible).