I created this Stevenson Screen for our outdoor thermometer. There's plenty of similar designs on thingiverse, but I'm also learning how to create such things with Fusion 360, so it was a learning experience as well.
There are two parts to this - the main base, and a lid that sits snugly inside. There's a third .stl which contains a single louver hoop as a test print if you think this design might be useful, but don't want to wait 6+ hours just to see if your thermometer will fit inside.
There's a fair bit of support required - I included a picture at the end of the print how it looked with all the support structure still attached (I sliced via Slic3r Prusa Edition).
Here's the Fusion 360 design.