Approx. 7" of 1/4" knicker elastic
Outer cover of electric twin cable
Nylon to pull elastic through outer cable
Bobbin to pull spool nylon through sleeve
Put elastic into nylon loop, feed nylon through cable outer, and then pull elastic through outer to within about 1/4" of ends.
Push eye of bobbin through outer ends, feed your nylon from spool through eye and pull through, slip tidy over spool, and tighten any slack. If you have made a spool holder fit onto this. No more unravelled spools in your pocket.