Sash window extractor fan

This model allows some wings to be attached to some fans so they fit perfectly in the upper (or lower) opening of a sash window.

I mainly use this to keep the kitchen steam free whilst cooking, but it's also great for keeping a room ventilated whilst soldering or 3d printers are running.

I used these fans (from amazon)  https://www.amazon.co.uk/gp/product/B08GP622YS?&_encoding=UTF8&tag=errm-21&linkCode=ur2&linkId=f009797ad9f3e0f3bdd71106541bddfb&camp=1634&creative=6738 but since my model is parametric you should be able to adapt the idea to any similar fans that have bolt holes in the corners.

The stls are sized for 4mm polycarbonate sheet, that I had left over from a greenhouse.  You could easily substitute perspex, or even thick coregated cardboard, be sure to adjust sheet_thickness in OpenSCAD if it's something other than 4mm.

The spacers lift the sheet so it will sit neatly over the fan wire shrouds, then the sheet clamps between these spacers and the clamps.
 

The nuts should slot right into the clamps so you can tighten the assembly with a screwdriver, you may want to test the dimensions of your nuts to get a tight fit by printing one of these testers first https://www.printables.com/model/215361-openscad-hex-nut-test-print-m3-m4