I made this Lady Loki costume for a commissioner in 2014. It is made of high-quality Monece satin, just one step down from bridal satin.
The dress and coat were spliced together from Simplicity 3685 and McCall's 3826, with many, many design changes. The most time-consuming addition was all the gold bias tape edging, since I used 18 yards of it and it was all homemade, not pre-packaged! (I treated myself and purchased a bias tape machine, but it still took a considerable amount of time to make and more than two hours to pin on before stitching.)
The horns, headband centerpiece, and cape clasp were all 3D printed from my husband's designs, then attached with E6000. The headband is made from satin over Peltex, which is like very dense quilt batting or extremely stiff polar fleece. The back encases a strip of elastic to ensure a tight fit. The cape clasp attaches with rare earth magnets.
All credit for the costume concept and reference image goes toBakaNekoSango.