The flag broke off my mailbox. I could have grabbed a replacement from Amazon for $10, but instead I decided to make my own. This is a complete replacement with the flag and bracket. My hardware was 10mm and 5mm which fit in the existing bolt holes on the mailbox. Since this is specific to the mailbox I have, I have also included a STEP file for easy remixing.

I printed this at 0.2mm with 3 walls and 30% triangle infill in PETG. I would also recommend ABS if you have the means. This will print fine with PLA, but it will not last in the elements.