We have vinyl double-hung windows that can tilt in for cleaning, but there's nothing to support them in the tilted-in mode to let me keep the windows open when rain is forecast. Thus, the Window Hook was born!
I also added the Sketchup file in case anyone wants to modify for their own windows. The inner dimension of the big hook is about 32mm for my windows, and the whole thing is about 156mm long.
Printed in PLA as that was what was in the printer. No special settings needed.