In my office, the window holder broke. It was made out of a material, that visibly degrades under UV light. I did not want to go buy a new one, since this is a rented office. Instead I did what I usually do, and fixed it in DIY fashion - by 3D printing it. Having a window holder not only enables controlled ventilation but also enhances safety and comfort within the living or working space.

A new window holder on a left and an old, broken one on the right

TinkerCad link:

STL file: download