Touching again on the blind eye salmon hook method, a method i used to use was to take any large single salmon hook and bend it. What you do is heat it and staighten out or snip the eye. Heat it again and bend it so that you have small bumps along the plain of the hook that increase in size as you get towards the bend. When you have achieved this, heat the whole hook and drop immediately into hot water to temper the metal.
It's a bit of a pain to do but works very well. It's a method that I used to use that I forgot all about until this thread. I may start employing this method again as, it is very effective at holding the tube securely.
Also, a lot cheaper than the mandrels and special tools.
Hope this helps somebody.