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.
Ryuu Productions FTW
Katsucon 2013, Otakon 2013
Costumes in Progress
Neo Queen Serenity Manga Version
,Haruko Haruhara- FLCL
, Yuuko Ichihara-XXHolic Riding Habit
,Belldandy: Ah Megami Sama Blue outfit
Maybes Sailor Jupiter Manga Version
andSailor Jupiter Fruit Maid Version