I'm looking for advice on building a backbone style helix

I'm planning on using a backbone style helix on my layout.  A backbone style is a helix built by curving a Masonite board to a set radius (in my case it will be about 32") and running on alternating loops one loop on the outside of the backbone a larger radius then transitioning to the inside of the backbone to a smaller radius.  The transition takes place in an opening that will be in the back of the helix.  An example set of drawings of what this looks like can be seen on page 70 of the 2008 issue of Model Railroad Planning followed by a description of what a backbone helix is.  They also show a few examples of ones that were actually built. 

The advantages of this type of helix is that the outside loops can be seniced and thus you will see the train on alternating levels so it's not out of sight for to long.  Plus I'm thinking of placing the station in Yoe PA on one of these loops to add more operating interest.

I'm looking for anyone who has ever had some experience building one of these who can give some advice on how they built it.  I have in my mind how I think it will go together, but any advice would be much appreciated if you have ever had any experience with this type of helix.