Having marked out the plywood with the measurements provided on the plans it was time to join up the dots. I'd seen various methods of doing this but came up with a simpler solution. Using a long thin batten and quick release clamp at one end I bent the batten and clamped the other end while it was still bent. This gave me a gentle curve to play with. It was just a matter pulling the batten into place and joining the dots with a soft pencil. Worked a treat! Bottle of Diet Coke and TV are optional (but necessary!) extras.