Because I do a lot of throws, I like the more substantial grip that rope offers. Colecord just feels kind of insubstantial when you're using heavy heads and need to grip the cord as often as the handle. So I decided to find a way to get my flowlights onto rope cords.
Getting the rope into the crystal cases was easy. Cut off the smaller loop at the closed end of the case, and drill in a hole big enough for the rope (in this case, 5'16"). The hard part was getting it to stay in. The approach I went with was to use a small piece of colecord to act as a plug, and to simultaneously whip the end (singeing the rope to melt the end tends to make a hard, wider part that's hard to push through the hole in the crystal case). The colecord is wrapped around just once, and sewn into the rope.
This leaves the open ends of the crystal cases facing out, so I've used twist ties to keep the lights snugly in place. I also have some concern that the sewing on the colecord plugs may be too close to the end of the rope, and may gradually simply work its way out, so I'll have to see how it holds up in the long term. So far I'm liking it better than the couple of other solutions I've seen/tried.