Finally I cut it out and added some interfacing...
When I was ironing the edga for sewing it on the grey part, the iron must have been too hot ・°・(ノД｀)・°・
Moreover... since I have some problems with my wrists recently, I can't go on attaching gold to the black borter o(；△；)o
How to finish my cosplaylike that!? （ｉДｉ）