Model originally uploaded to Thingiverse at https://www.thingiverse.com/thing:3816153.
I got a set of ring pathlights and my wife wanted to mount one on our deck and the included stake mount wouldn't work and the light by itself would fall over in the wind. So i decided to model the stake mount and make a flush mount.
I would suggest Pet-g you might be able to make abs work if you account for any shrinkage. Pla would probably get brittle and break before too long.
There are marks so that you can see which way the sensor will be pointing. make sure you get that set right before you put the second screw in.
i printed it with 3 perimeters and 30% infill just to make sure it would be plenty strong.
This thing was made with Tinkercad. Edit it online https://www.tinkercad.com/things/09wixu19P4G
update 9/27/2020 I had a request for the spike that comes with the light and as luck would have it i now have a 3d scanner so i uploaded the scan as it came from the scanner and with a little cleanup done. enjoy!