I've read in numerous places that the rain gauge cover is not deep enough on the WS-2080 weather station rain gauge. I have seen modifications that call for taking another cover and flipping it upside down and gluing it to the cover (thus creating an extension). This keeps high velocity rain from bouncing out of the tray and creating low readings. Why buy another cover when I can print one for free? This should solve the problems associated with low readings and should fit a number of weather stations that use this tipping rain gauge (check the picture). Customizable height. Part has been printed and appears to be just slightly undersized. I increased both the inside length and width as a fix and re-uploaded. I printed it 1" high, which I think is just a little too short; 1.5" (38.1mm) should be perfect. I have also made it fully customizable - I think one could even create a circular wall as well if needed (just make the length and width just shy of twice the corner radius). I have updated the STLs to reflect the 0.5mm increase in dimensions.
Customize to the height you want and then print in ABS (I don't PLA would handle the weather too well). Paint the piece with a UV plastic paint (preferably a light color) and glue to the top of the rain gauge.