Built using 1/4” luan and 1 x 2’s and yellow glue. Builder in pictures is Dave.
One change that I would do if done over would be to spike track not glue it to cork. This would allow the track to move. I did have about 4 ft come up from expansion. This helix has now been in service for 11 years and was moved once.
If you have questions contact me at ahouston3@charter.net