Some casement or awning windows are opened/closed by turning a handle that fits over a spline. These cranks seem designed to fail before the window itself when torque is wrongly applied, so replacements are sometimes needed.

This handle press-fits onto a spline that is part of the window. Rotate under gentle pressure until it locks into place, and then press harder. It is designed for an 11-tooth spline with an outer diameter of 3/8 inches, but the FreeCAD file is included if yours is different.

No support material is required. Mine, printed out of PLA with default settings on a Prusa Mini, seems to be strong enough.