You could do i-cord, I suppose, but I think ribbon would be nicer. To stop it from fraying, get a lighter and hold a flame near the cut edge of the ribbon for a couple of seconds. It shouldn't be close enough to light or even singe, but the edge will kind of shrink away from the flame just the tiniest bit. Blow on it and then touch it, trying to fray the edge with your fingers, and if it frays, cut off the last 2 millimetres and try again. You should feel the edge of the ribbon slightly plastic-y.