I thought you might like a little more info. Here is a better look at the acrylic plug.
For a 12 inch acrylic rod it cost under $15. A 20 foot piece of 8mm fiber optic cable cost around $50. So for under $70 I was able to make three whips. It ends up being cheaper to make them yourself and you get better quality.
Also the saber I use has a Diamond board. So the whip cracking sound is from a sound font not the actual fiber optic cable. Just to be clear. I used the sound font called "Flaming torch". It was made by Darth Vigorous and here is a like to it...
http://www.saberforum.com/index.php?topic=32748.0And here is a link to the whip sounds I added to make my flaming whip diamond save...
https://drive.google.com/drive/folders/137l3U4cJBpgQEWR1GeHHG8tIOazXEv8f?usp=sharingWith the sound files you could make a fire whip font for any of Ultra Saber's sound boards. For a whip, the diamond board has no advantages over the other boards. You don't really do stabs or spins with a whip. I mean you could but... for a whip, an obsidian board is just as good as a diamond.