Pier, I followed the link to your friend who was making them and got to Facebook but the massage was “product is not available”.
I already have the CPL Mag filter I was using with my Blackvue I can use, so was thinking.
I’ve measured the lens OD diameter on the 0805 and its 17.21mm Ø. On the blackvue, the mount (for the CPL) ID 20.65 mm Ø while the lens OD on the DVR is 20.44mm Ø a difference od - 0.21
on advantage on the 0805 that the Blackvue doesn’t have is, around the lens barrel it has a minimum of 3.5mm of flat surface and then to the centre of the 0805 where there are those perforations, a large flat surface,
My old Blackvue mount was held on to the DVR lens barrel by friction as the mount diameter was about 0.21mm smaller then the lend barrel, could I not do the same with the 0805?
Have a (for a better word) a plastic material with a thickness of 1.5mm and an OD diameter of 32mm, same size as the one for the Blackvue that works OK with the Mag filter I own. then have the ID hole 17mm, same difference as on the Blackvue - 0.21mm
this way (hopefully) the friction will hold the mount and CPL to the 0805
the mount something like this images of plastic washers, I found these images from google, but this explains my thoughts