I went and purchased an 8’ (.45m) cap for a porch screen system.
it was about 2” (50.8mm) wide and about .125” (3.1mm) thick. Using a jig saw, I cut it to the proper length and width. I needed to sand the thickness a little to make it fit. Also softened all edges.
I slide it in, and it seems to work. I’ll find out shortly. It was cheap enough.
