I designed the helix to use trapezoidal pieces of plywood to create a dodecagon (12 sided). The helix has a 36" radius at a 1.75% grade, which gave us a 4" rail head to rail head separation. By using the trapezoidal pieces we were able to cut the helix out of 4 1/4" plywood strips with very little waste. We used 2 pieces of 1/4" plywood, which was laminated with 1/2" brad nails and plenty of glue. We staggered the joints by one half piece.  We assembled all the layers together on the floor and then moved the assembly to the frame. We then temporally installed 2x2 to the frame vertically around the inside and outside of the helix.  This gave us something to clamp the upper levels to while working on the lower levels.  Risers were then installed on the bottom level to give us our grade. After the first level was attached to the risers, we lifted up on the other levels and clamped them to the 2x2 to get them out of the way so we could lay track on that level. Once the first level had track installed, we then installed the blocks that gave us the correct vertical separation. We then unclamped the next level and lowered onto the blocks. Next, we installed track on the next level and so on until we had gotten to the top.       Cody Hilliard