Here are the three ladders with all the miscellaneous brackets, pulleys, and guides attached. Lower ladder in the back, upper (narrowest) ladder in the front. I also added a black wash (naturally! ) where the rungs meet the rails.
Paul... the one ladder that was in the kit (the narrowest one) was used as a template to build the replacement in wood. Then looking at the instruction book illustrations, I saw how the three ladders nested into each other, so I measured the width of the narrow ladder to get the needed width of the middle ladder and cut the rungs to the required length... then after building the middle ladder I measured the width to get the needed width of the lower ladder, etc.
The way I built the ladders was like this: I laid the one existing plastic kit ladder down right at the edge of my work surface, then laid a wooden ladder rail against it, laid 2-3 rungs down to get the correct spacing between the rails, then the other ladder rail. I made sure the wooden rails and the ends of the kit ladder all lined up, then I laid a couple of thin flat pieces of scrap wood down on each end, on top of the kit ladder and my wooden rails, and used a couple of large spring clamps to lock everything down tight. I laid down two thin strips of styrene between my wooden rails, to keep the rungs properly centered within the rails, then just glued each rung in place between the wooden rails with a drop of super glue at each rung end, using the kit ladder as the guide to space my rungs. I used a small piece of wood with a perfect 90 degree angle that fits between the rails as a small square to square up each rung before I glued it into place. Once I had all of the center rungs glued in, I removed the clamps and finished gluing the rest of the rungs onto each end of the ladder, still using the existing kit ladder as my spacer guide.