I have first hand information about these particular ppl becuase I happened to have known some of them. I will tell you about how their “uniform” clothes came into being, with the dress and apron.
They were looking to be “tznius” on a higher level. So they sent one of their husbands to tell the “cult leader aka rebbe” that they were looking to have a dress code of tznius. He sat and sketched out an outline of what it should look like.
Then they took turns having a dressmaker make them each a dress.
THey call it M’meshbaos zahav L’Vishu, from Tehillim 45 where its says “her raiment is made of gold settings”.