Interesting technique Alan, thanks for sharing.
I'll have to give that a try. I've been experimenting with heat stretched tube - plastic tubing, drinking straws, pen ink refills, etc - but none will successfully pull out to a thin diameter without dissolving into a messy goo. I used to have some success with plastic cotton buds, but you can't get them here anymore for understandable environmental reasons.
Keeping a wire inside when stretching is very thought provoking and will send me back to the test bench to try it out.
Cheers
Sandy
P.S. I wish one of the cottage industries would attempt hollow turnbuckles that you could pass mono right through then right through the wing. Desperately fine tolerances of course.