I've been using something like this for years now with both Inon and Ikelite (with optical trigger adapter) for years now. 2 or 3mm side/end glow cable. Available on Ebay for about $7 for 5 meters. It's tough, durable, easy to work with. The transparent sheath it's in make for an interesting look too, you can see the red led trigger glow though the cable if you look carefully.