I had a very good idea which I’ve never seen anyone do before (perhaps because it’s slightly convoluted) but with doll clothing/accessories, even within a scale there are significant size variations. So you could buy a 1/6 item which was too small or too loose.

So I have devised petite, medium and BJD sizes for each scale, meaning the items have a much higher chance of correctly fitting and looking good, which is the point of dressing up your dolls.