@rick I mean I get that Gojo could wing something like that. If you have years upon years of sewing experience and patterning prowess (these dolls certainly do not have any sewing patterns)
It should be an easy thing for him to take some measurement and tailor stuff for Marin.
(Though the measurement taking might be

)
Also I cannot fathom the torture that it must be to create these small costumes for the dolls. Super small and intricate stuff is the baine of my sewing existance.