The old Helix originally pictured was made using sewer snake steel. I have studied a few of these. There does not seem to be much information regarding who originally made them. There are a few of them around including the "figure 8 double helix" all with the same steel bar track construction. I tried to buy this one at the Spring York 2014 show , he was pretty set on $2800 then.
I am going to build a similar one out of current track. The Corkscrew inner outer return Helix are fun with some early tin running around them.