Trying to replicate a detailed circle blend. Results not the same

Please see files attached. First file is the original by the designer. He knows I'm trying my best to replicate his work for learning purposes. Second file is my attempt (not worried about getting the shape exact just want to figure out how he acheived this effect). Third and fourth files are the tutorials that he's sent me to help. The last tutorial is obvious and I've figured out how to blend to a path. The first tutorial I can't figure out how to integrate in order to acheive the blend from outside in that this tube shape has.  Any help greatly appreciated. Really want to crack this code. Thanks