After all my other coroplast panels were assembled with my designed brackets, I found the lid was sagging. I built an interlocking edge support that could span across the lid and is supporting the drooping edge fairly well. I was limited by print bed size. I printed two of them diagonally at one time and it worked great.

I would suggest using a brim to hold those narrow edges down.

Creality

Ender 3

Yes

No

0.20

As you see fit

There are a lot of long layers here. Do what you need to do to hold the layers together (reduce fan, print slower, bump extrusion flow, etc) as your situation and printer requires.