Take a look at quilting pins and see if they are a good length. They are longer.
I’m seeing “quilting pins” no more than 2” long. I would need something 5” to 6” long and at least partially hollow (like tubing) so I can pass the “string”* up into it), then crimp the “tube” onto the “string”.
*Usually the “string” 1/8” to 3/16” diameter, so, it is more like “cord” or light rope.
???
It sort of seems like my Mom had something almost like this for making Afghans, but IIRC (questionable) they were plastic and solid. But I may be thinking of something else.
Thanks.