This window handle is compatible with metal-plastic windows and it is fully 3D printed. It consists of four parts.

The front part of the handle, which is inserted into a window, is printed with 100% infill which ensures that it is not broken easily, while the rest of the handle is printed with 20% infill.  Additionally, special stoppers are added on the big cover to limit the motion of the handle from 0 to 90 degrees in order to avoid the twisting. Overall, the handle is quite strong. 

You can glue the cylinder to the handle as shown in the photos.