So this has been another "educational" moment for me. As a review, the first four pictures below outline the fabrication process for the fiberglass fairings to fit the fuel drains under the center section, done in Feb and Mar 2022.
A few days ago while searching the loft for something else I had squirreled away, I blundered across these fairings I had stuffed up there last year. Nope. It was two years ago! Anyway, they're all warped now!? WTF? They are proper fiberglass/epoxy layups and not supposed to act this way, as far as I know.

Pretty sure the culprit is the high-build primer I had sprayed on them to fill the fabric finish on the outside of the layups. It was a two-part, catalyzed PPG primer, so I figured it was going to be pretty stable. Guess I should have read the fine print, or the FULL instructions.
Everything was fine spraying and wet-sanding them out, but over time, the primer layer must have shrunk some as some polyester layups will. The fiberglass was thin enough and the primer thick enough, that the one overpowered the other.

Anyway, what to do about it? A simple fix would be to blob a bed of flox around the inside of the flanges, then press them onto a flat release surface... and wait.
Following their release, wait again for nice enough weather (non-life threatening) to take them outside and grind off all the unwanted bumps and lumps. (very, very dusty).
Losing my enthusiasms for making chemistry play nice with others, I instead made a shout-out to my son to see if he may be interested in a 3-D printing project.
I sent him some basic dimensions, and he launched back the two "Fairing" images below in about an hour. Pretty much exactly what I'm looking for. Since it apparently wasn't much of a challenge for him, I suggested he work up a teardrop shaped set... No, these are fine. Really. He said something about PLA, carbon fiber mix should paint well.... k?
I told him I wasn't in any hurry and could pick them up the next time we meet up. He's in the UK, so I should update this when we get back from his house in Sept.

The beautiful red Hatz pictures below show these in situ under the center section fuel tank. Pictures are of John Hanson's Hatz Classic.