Blind hem. These were hand stitched. I've circled the visible threads and drew a parallel red line next to them to make them more visible. If you machine stitch your ribbons you'll have a visible seam, which isn't what you want. The presser foot would be too wide anyway, and to use a blind presser foot, it would be even wider, so you want to hand stitch. You can see from my markings that the few visible threads run diagonally and are uneven which indicates hand sewn. The stitches are still there on the real medal, covering the screws, otherwise those would be visible.
The original source was unlikely to be ties as Luke's poncho was made of the same material and the trim on it was unbroken. If they'd used ties, you would see a lot more seams to make up the length necessary to cover the edges of the poncho. Mollo and his team had rolls of this stuff.
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