It is a real simple design. It is basically to 45 degree angle pieces that sit on each other.
There is a strip that is mounted to the wall with a 45 angel outward:
Then on the back of the panel is another strip with a 45 angel outward:
As you can see very simple to work with. I used 3/8" thick starboard. They were expensive to buy in full sheets but it works great, holds up well against the water and lighting and cleans up very well.