billnikon wrote:
Don't do it. It will jingle around every time you shoot your camera. It will get in your way and be a general pain in the butt. And you will look silly. Please, do not do this. If you insist, B&H has them and has a little sticky thingie that sticks to your lens cap, that way, when you tire of it, which will be very soon, you can take it off with no damage to your lens cap.
Locally, the cap keepers cost around $5 each - and all it is, really, is a bit of elastic with a sticky thingy on the end. So I made them myself, one for each lens cap I have (and somehow I have more caps than lenses): With 1/4" elastic from the fabric store, I can make 15-18 cap keepers for under $3.