Well, upcycling clothes is a must to me! But since some years ago, I was fabric holic, I had bought basting material, when I sew bags, about 8 meters (!) and I use it for situations like this...! But once, I was in my sister's and I didn't have that, so I used for the in-between part (between inner and outer) double denim fabric and it was perfect! Nice job here!!