Blue Sparkle
Contributor
I'm amazed we've got 6 pages of posts on homemade reg bungies when for a mere $ 8 @ Divegearexpress you can just go buy one that's equal to or superior to any of the solutions posted so far:
Regulator Accessories - Dive Gear Express
In addition to what Devon Diver said, I've got bungie just sitting in my bosun's kit, waiting to be used for this or a number of other projects. So for practically no effort and money, I have a necklace that can be made to just the right size for me, plus supplies for more/spares. Not that $8 plus shipping, plus my having to order it, plus perhaps another $8 for a spare is the end of the world, but I'm just explaining why it may not always be "amazing" that people would make their own.
(Yes, I ordered bungie in the first place, but that's a sunk cost since I always have it on hand in the kit anyway, plus, even at a per/foot rate it's fairly inexpensive.)
Many options for how to do it, and not all are "lesser" than the Dive Gear Express one (that said, I have happily ordered from them, so nothing against them either; in fact, I think I got my current supply of bungie and surgical tubing from them).