We made ours and a shade for the front windshield. We bought the material at Lowes, they sell it by the linear foot in a six foot width. We bought 15 foot for the patio and 11 foot for the windshield for about $60. It is found in the outdoor dept as shade cloth. My wife hemmed up 1 inch around the patio piece. On the windshield she hemmed 1/2 in on the vertical sides, 1 inch on the bottom and we folded the top down to fit. She sewed that about 1 inch in but there is about a 2 foot flap. For the patio I bought a grommet kit and placed a grommet every 2 foot on top and at each end on the bottom. I also used Goop brand glue at each grommet making about a 2 inch patch of glued fabric around the grommet. It was a trick I learned in the Army to keep grommets in stretchy fabric. I bought a package of hangers from an RV place that slide into the grove on the awning and use an S-hook to the grommets on the patio shade. I tie down my awning when I use the shade and use bungee cords at the bottom of the cloth to the stakes on each side. When I roll up the awning I take the S-hook off but leave the rubber hangers in the groove.
One thing I noticed is that the rubber hangers for the awning has two sides that are different in size (one thicker than the other). I am not sure if the different manufacturers have a different size for the slot or if it is different models of the awnings (ie electric vs manual). But this indicates that the slot can be one of two different sizes.
For the windshield my wife sewed loops on the shade and we use command hooks to hang from. I remove the hooks before we travel. I have placed a small mark where the hooks go.
Might not be as easy as the pre-made patio shade and custom windshield covers but for $100 all in for both it works pretty well.
Mike