Had a lot of warped window screen brackets in our travel trailer so I put together these models for our use case.  I'm by no means a CAD expert so the tolerances are very tight, I trimmed a little off the corners to make the fit work but they are very snug.  These run anywhere between $2-5 each online and cost only a few cents and some time to produce.  The radius bracket is 2.5" and the others are the respective 90 degree fitting.  Depending on climate you might be able to get away with PLA but PETG or ASA might be better.