Easy Warren.
I have done a good dozen or so of these and shipped into London for a Tanning Chain plus other places.
Correx Back to back with the outer edges tapped together and a 2 part pole run up the centre.
Pole I always use 47mm square timber. Run them down a router to radius the corners, then sand.
Run one part of the pole up the centre of the 2 boards and use polytop screws each side to screw into the pole. The pole through the centre of the panels I offset slightly so the lower section that fixes to it is centred. Fix them side by side with a sensible overlap. Bolt through in 2 places and wingnut.
Clear as mud 😕