I've never used them, but when looking for similar items to improve my knife lanyard I bookmarked this page: Shaotech Lanyard Accessories. They seem to have a real good variety of hardware (including the whistle cord end I was looking for).

Also, I know MEC up here stocks a limited variety of these type of hardware accessories so it might be worth trying your local REI or similar.
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Victory awaits him who has everything in order — luck, people call it. Defeat is certain for him who has neglected to take the necessary precautions in time; this is called bad luck. Roald Amundsen