I believe from my experience of seeing this trim, it's really just gold pvc thats lightweight enough or has enough natural stretch to go around edges. I've seen both folded over edges or clean edged and also unfinished edge or cut into strips and sewn on cause it's easy to do...etc.
I've only ever seen anything similar at Joann's in their trim section, it's like a gold belting...but it's already glued down, you could try cutting it in half to see if it is useful in any smaller pieces.
Creamy Mami- #Fightlikeamagicalgirl version
Yuri Kuma Arashi: Kureha Magical Girl Bear form
Formal Pearl: Steven Universe
Femme 1920's Riddler
1800's Inspired Ravenclaw
NoFlutter Artwork Jupiter Armor
NoFlutter Artwork Jupiter Bulesque
Harry Potter Regency looks