[How do I mirror something exact if it's not 100% equal in rotation?]

2 minutes ago, Pixey said:

Hello @DeltaLCR and Welcome to the forum   

 

You could make a new layer above the image.

With the Rectangle select, use the Move Selection Move selection tool.

Hover over the yellow stripe until it matches the size/position.

Use the Paint Bucket to add the yellow color.

Use feather, or AA's Assistant to clean the edges.

Flip horizontal and align.

Thank you!

[How do I mirror something exact if it's not 100% equal in rotation?]

I accidentally rotated a P-51C i was editing for a project a bit too far, causing it to be asymmetrical. I want to copy a stripe from one side to the other but I don't know how to no matter how much I have tried.