When laying out the benches keep in mind you will need overhang for the cushions. The center bench was one inch wider than the cushion. This gave a half inch overhang on each side.
The back rests were framed from doubled up two by twos, and radius cut using a saber saw. To make the plywood bend I had to sand the top layer of ply off the back. When I tacked down the plywood, I used wood filler underneath to eliminate soft spots.
The table was made from a butcher block table I picked up off Craigslist. I had to add an extra post for stability. To make it into a bed the posts are removed and the table sits on two rails I made from two 1 1/2 inch strips mohagony. Hope this helps.