How I came to design this:
After the mortar used to mount my window hardened the lower side of the window, along with part of the lower frame moved a tiny tiny bit down, causing the window closing mechanism to not catch all 3 of the brackets resulting in lopsided window. Unable to find a longer "bracket" or at least one without the window (they only come as sets) I decided to design my own.

READ CAREFULLY FOR COMPATIBILITY:

This design is for windows that have channel at least 4mm wide.

The part in the pictures has been printed in BASF PET Orange upside down with supports.

Printing temperatures (Celsius) for the filament used:
Nozzle: 220
Hotbed: 70