On both sides use a texta and mark the line where it exits the tubing. Pull
line out 1cm or so and tie a single knot on the marked area of line. At magnet
end pull line back, so the knot is tucked under the heat shrink tube.
With the retainer sized to fit take a heat gun orpowerful
hairdryer and heat the tubed areas all over for 1-2 mins at close range until a
smooth finish is obtained.
Snip of excess line.
