I'm definitely up for having Illya learn how to make clothes, since she only has her normal winter outfit + any magical transformation outfits that Ruby makes explicitly for her. It will definitely be like an arts and crafts project, so she won't have any problems learning it personally, although shenanigans might happen because her kaleidostick can kind of transform her into various outfits (that are definitely Not Normal because Ruby's taste is weird).

So, uh, if anybody wants to see any magical clothing transformations, that's probably going to happen when they decide to come as a group and start wanting to make clothes/sewing.