It is very easy and looks like the oem. You can adopt this idea with other dash cams with protruding lens.
so let's start. lens in 0801s is small. the smallest cpl I have found was 24mm- still too big for 0801s. BUT it has a metal ring inside it. All You need to do is go to a store and buy...
I have seen videos and it looks like it helps a lo to have filter. Can someone confirm if it helps and know if there is someone who sells it for the DAB205