A couple uses I have found from using my DH's old strings:
Cheese cutters
Best cutter for homemade soap loaves, either if someone makes themselves, or if you buy them from someone else
Cutting rolls of cookies, cinnamon rolls very nicely as well, use as you would string to cut them without smooshing them.
To make the above safe without hurting fingers, hubby has secured them on wooden blocks or dowels, so to pull tight enough to do what is needed, but without having to twist around fingers (which could cut). He's been trying to perfect this to make a reusable item similar to bought cheese cutters, but has yet to do one that works well...lol ... View related article.