My friend Stephen improved my sliding window rain screen by making larger cutouts at all four corners. I think this will keep out the rain better.
Update Feb 4 2020.
Here is a very quick and dirty pdf drawing of the screen. My old draughting teacher would be appalled. The width of the screen could be adjusted to suit, my first version was narrower.
window-screen-drawing-v1-1.pdf
shooftie 
#1 by albert ferre i gisbert on July 9, 2016 - 4:09 am
http://alcasabricos-alcasa.blogspot.com.es/2016/07/protectores-de-lluvia-para-ventana.html
#2 by albell on July 9, 2016 - 9:27 am
Nice job Albert š
Alistair
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#3 by Gnarlodious on May 29, 2017 - 1:52 pm
Do you offer a PDF cutting pattern for that?
#4 by albell on May 29, 2017 - 5:59 pm
Hey there,
No I don’t have plans but I do have some rough measurements of two I have left. I gave away some…
Anyway, the larger of the two is 17×11 1/2″
The smaller is 17 1/2 x 7 1/2″
Both 1/8″ lexan.
So you see there is lots of leniency in the dimensions. I have to say that pleases use lexan.
The notches at the corners were something we played around with. It came down to making a notch that wouldn’t let water in. Roughly its 1 3/8″ by 1 3/4″. The larger dimension in the vertical .
Cheers
Alistair
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