Large spool of seemingly heavy duty thread/twine/string. Possibly

Michael OReilly Art Blog — Brightwire Designs

Bobbin Stitch Nerd

What is the best material a to use when stringing hunting bows, etc? - Quora

100% Heavy Duty Thread Package of 6 Rolls 3800 Ft x Roll Roll Weight: 8.5 oz (0.53 lbs)

Heavy Duty Spool Sewing Thread for Bags Stitcher Closer 3600 ft (6 Rolls)

Heavy Duty Sewing String Tread Spools. Size of the spool - appx 750g. Strong All Purpose - leather, canvas, furniter stitching polyester

Heavy Duty Thread String Large Spool for Leather, Canvas, Furniture Stitching - appx 750g (Brown)

Fabric Supply - Thread & Twine

Weed eater string soak? : r/lawncare

big grubby old spools of string, primitive white cotton cord & sewing thread cones

Fabric Supply - Thread & Twine