I made one for my bikini top. It was really easy and cheap.
1- 2 1/2 inch double 90 degree pvc cut in half (longways)
2- 2 1/2 inch to 3/4 inch adapters
1- 4 foot section of 3/4 inch pvc cut to size. I measured between roll bars and cut. The spacers provide enough length to make it bow. You may have to play with the length.
Painted mine flat black.
Have not messed with one for the tonneau yet.