This is a corner mount for the Netatmo anemometer. You can use this if you cant easily access your rooftop or have no way of mounting it there. While mounting it directly next to a wall isn't optimal either this should work fairly well.

Printing

You can print it in the orientation uploaded without supports and since the anemometer isn't that heavy standard strength settings should be fine. 

As for the material, any outdoor compatible filament should be fine (maybe don't use PLA).