Wirdow Hook for Decoration
This small hook is meant to fit at the top of a window from where you then can hang arbitrary decoration into your window. You can use twine or fishing line as long as it fits through the hole of this hook. Then make a knot at the top.
The picture here was my first try where the hole was too small so that it got filled while printing. So I just drilled a new one. I increased the hole size slightly so that should not happen that easily. But depending on your printers accuracy, you might want to tweak that a bit further.