bobby/hair pin...right? You know what I am talking about? No? A knitting Nancy? French knitting? Tomboy stitch? Spool knitting? I-cord? Idiot cord? A writer friend of mine was not sure what I was talking about but I am sure she will realise what it is when she Googles and sees it.
I am sending her off to look at Prudence Mapstone's "Knot Just Knitting" site as well. There is some of this apparently useless stuff being used there, along with a lot of crochet and some magnificent pieces of art and wearable art. Prudence is a friend. It was her stall I was trying to help out on while she was teaching in Ireland. Prudence "scrumbles" - think crazy patchwork done with yarn, crochet hooks, knitting needles, imagination and colour sense. I-cord is an essential part of this.
What I am talking about is of course that knitted cord you can make by looping yarn around the four nails and then using the pin to loop the loops. Almost all children do it by the yard or metre in school. Now that wooden cotton reels are a thing of the past they do it on toilet roll tube with four ice-cream sticks. This is not as durable. It does not require the same degree of fine motor coordination. It does not produce the same results. (This may be why my father has made dozens of "cotton reels" in recent years.) You can do it on two double pointed needles as well - useful if you want to do "attached i-cord" as a border on a piece of knitting.
When I was in primary school some of the other students produced long lengths of it. One boy made enough to go right around the playground - and he did not cheat at the corners. He had no idea what he was going to do with it. He just went on making it.
I think Mattel brought out a machine for doing it - probably in Barbie pink. There are now other machines for doing it and one for doing it with wire as well. You can just crank a handle. It is faster but is it as much fun?
So, what do you do with it? You can knit with it - knit the knitting. One yarn company actually produced some yarn like that...nice colours but madly expensive. The end result was - shall we say 'interesting but not practical'? You can use it for borders and for decorations. It makes great Celtic knots. They can make good "frog" closures. You can wind it around for place mats and pot-mitts and hats. You can scrumble it into a vest or other item.
It is an essential art which really needs to be learned in childhood - childhood at any age.