Window opener handle with 7 mm square insert.

It's usable if the window opens easy enough. Don't use it if you feel that the handle starts twisting but the window locking mechanism is not moving. If it breaks you might be left with a plastic part inside the window mechanism that can be difficult to get out. It's the square part that will break if anything.

I printed with PET and 100% infill and used supports.

Fusion 360 file is included so you can modify to your needs.