Window Box Fan Retainer Clip

I live in a part of the world where air conditioning isn't _really_ necessary, and during the brief part of the year where it gets uncomfortably warm inside, we usually just put a fan in the window. From time to time, though, I'd come home to discover that a surprise gust of wind had blown the fan onto my bedroom floor or sucked it out onto the roof. Luckily this is a problem easily solved with just a little 3D printing.

Here you'll find a clip you can print one or two of (I'm using two) fo