Here are the materials:
One piece of signmaker's material sintra or trovicel for the awning itself. It can be any number of things you might find at a builder's supply store, but it needs to be rigid and tough.

One strip of dywall edging. At least I think that's what it is, and I found it the bin at Home Depot that contains the metal edging that you put on drywall corners, and it was in the drywall section. It's used to hook the awning into the rain gutter, you can see its profile in one of the photos below.

A piece of 3/16 dowel about 14 inches long, but could be longer. It serves at the strut that holds up the awning. I would rather have used an aluminum tube or section of a fishing rod, but there is a critical design feature that is easy to whittle into the wood and tougher to make in aluminum or fiberglass--it's a notch that goes around the circumference of the upper end of the strut, about 1/2 inch from the end. It catches the plastic awning and presents it from sliding down the strut. The outward pressure from the bent spring on the base keeps the carved groove in contact with the hole drilled into the awning material to receive it. This is a surprisingly dependable arrangement, but like all awning designs, there's going to be some level of wind it can't tolerate.

A Stanley Spring Doorstop #81-9050 SP7092 also from Home Depot. These are the things you put on your hoe's baseboard to keep your doors from hitting the wall. They come two to a pack for $2.39 around here. Take off the rubber tip and use it to replace the missing one in your house : ). Note that this gadget come in two pieces, a base and the spring itself. The base mounts with a single screw and once it's attached, the spring threads into a hole in the base to keep it secure.

Magnet from harborfreight.com. It's actually a Magnetic Ground Block ITEM 30754-0VGA $7.99 on the website, but I bought several of these magnets for half that in the store when they were on sale. Remove the brass part and spring when you get it, you won't need that. The magnet conveniently has a recess in the top side that exactly fits the base of the door stopper. You'll need one or more washers to close the big hole in the magnet down to capture the head of the #8 screw and nut you will use to attache the doorstop base to the magnet.

Once you have the spring base fastened to the magnet, it's time to cover the base of the magnet with cloth or felt. I used a scrap of headliner, and left a tag sticking out I could grab and lift by. This magnet is very strong. If you don't use the cloth, you almost can't get it off and will surely scratch your paint. I use another one of these magnets to attach a 12v fan to my dash (an older diesel westy without a heavy plastic dash cover).

That's it, besides the silicon glue or whatever you're going to use to glue the top catch strip to the plastic. The dowel is just stuck down into the small end of the spring, it's a snug fit.