Here are a couple of pictures of the new platforms on my 2600.
They are made of 3/4" Sea board covered with cool gray Sea Dek.

where did you get them from and how much

I designed and built them myself. I bought the SS brackets from Dana Marine.

They are really great looknig. how did you get the side to bend upward on the side ones and down on the center one

I cut the material at 22 degrees and screwed them together, you can see one of the screws in the third picture, not to many glues will stick to the polyethelene. You can cut out the shape with a skill saw or a jig saw then smooth the edges and use a 1/2" round over router bit.