Found a metal one at Menards. The only part I don't like about it is it has a solid "roof". I wanted to be able to hang plants from the "ceiling" and they would get some sun and it would rain in and water.

It would be very easy to add extensions all around for plant hanging. Then you would have both solid shade and water proof area and plants. I am thinking something free standing that would butt right up to the eaves of the Pergola.