I made this about a year ago, and it still looks the same the day I installed it. So it has some robustness. The bad part is I forget some of the details. (Sorry! But you can figure it out pretty easily I think -- read on.)
I think the total cost was ~$30.
Step 1: Stuff You Need
(2) 8' lengths of flat molding. (The corners are rounded a bit to take the edge away.)
Staple gun & 1/4" or 3/8" staples.
1-1/2" flat plate. These might be called "repair" plates. (I forget.)
(2) flat-head machine screws, #6 or #8, length is ~3/4" (I forget this too.)
(4) nuts to match machine screws. I used double-nuts.
(7) Self-tapping screws
(4) screws eyes (You'll have to judge the size based on how windy it is where you are.)