Named shirring. However, the search it generates is very similar to smocking, which is an embroidery procedure that’s been around a lengthy very long time. But perhaps don’t google “what on earth is smocking” cuz evidently Furthermore, it refers to something that has nothing to try and do with sewing… https://rubber-covered-yarn87642.free-blogz.com/79061710/covered-spandex-yarn-no-further-a-mystery