I have a Cat Door built into my homes wall that is 6-3/4" wide, 9" tall and has retaining tabs for a cover that offer a 5/32" thick panel. That is ~171mm x 228mm x 4mm in metric. I made this cover to replace a old rotting particle board cover. Includes a small ledge for purchase when removing.

Built in two parts with a large lap joint at the center, simply super glue the two halves together and once it cures it is quite ridgid.

Made in tinkerCAD, Sliced in Cura

Creality

Ender 3 Pro

No

No

0.2mm

50%

used a 0.6mm nozzle, took about 10 hours to print both parts