Slowly, the knitting is getting done:

Should anyone else choose to follow this path, before you cut the thread to make the second turnbuckle, leave the thread long. No, twice as much as that - no, twice as much again.
It is easier if you can rethread the tube (put in the return thread) well away from the model. By pulling a loop out with the tube threaded on, life is much simpler. And thread is cheap
Richard