Wrapping wires with nylon / wax string
I call it lacing cord, as does Digikey and their suppliers.  However, Digikey don't stock it from either supplier.

I learned to use it while working installing equipment in a telephone exchange as a summer job 50 years ago - doubt if it is used much any more...

Wikipedia has a brief article, with pictures showing examples.

If I recall correctly, the lacing cord I've used was flat, like a narrow ribbon, rather than round like a normal cord.  Presumably the flat ribbon was easier on the wire insulation than a normal round cord.