The cosplayer wanted the OVA version, which is actually brown - I had only read the manga before, where it looks like Medusa is blonde or white-haired. But now I think I prefer the dark-haired version, too!
The braids and hairbuns are based on rubber foam, wrapped with extension fiber (mostly long wefts). Rubber foam is one of my favorite foamcore materials to use in a wig because it's so lightweight and flexible.
In addition to the 1000 beads already sewn into the wig, I bought another 10,000 beads for the cosplayer, so her dress would match the wig.
1 mid-length wig, extensions x7 (#6 - dark brown); foamcore, beads, elastic string, wire, fabric