I needed an elliptical ventilation opening for my garage.
I am providing you with the unmodified original file.

For those who, like me, have the Prusa Mini, I have also created Garage_ventilation_half and the left and right halves as STL files. (should be symmetrical, but I'll output them separately anyway)
Both halves then fit on the printer and can be glued together later.

Outer length 225 mm

Inner length 195 mm

Outher height 130 mm

Inner height 103 mm

Thickness of the bar 7mm