Not a Subaru, but still a homemade plow:
About two years ago I bought a new truck. I then modded my old truck, a 1986 Chevy Blazer, for plowing my driveway. I spent around 60 bucks or so, for plywood, lumber and hardware - for the rest I used bits and bobs I had lying around. It worked very, very well until the transmission blew and I had to have the truck towed away as scrap. But until then it worked exactly as planned - no drift could stand in its way!
First, I stripped off the front end as I wasn’t going to be driving on the street.
Then I built the plow itself. That’s 3/4" plywood and 2x6 braces with angle iron on the edges.
I attached it to the car using the bumper mounts and 2x8’s. I added the guy-wires to hold up the front end. I just wrapped them around the hood mounts and used turnbuckles to supply some tension.
And there she is! My redneck PLY-PLOW!
I’ve seen other versions, but none quite like this!