Well, I was bored today, and I have an excess of twine... So I decided to make a mug frog. It's not very fancy, and fairly easy to replicate. The toggle I used was a piece of a wooden dowel cut to size. Anyways, enjoy! :P I tend to make odd things when I'm bored.
(http://i882.photobucket.com/albums/ac22/undeadmudkip/DSC00593.jpg)
(http://i882.photobucket.com/albums/ac22/undeadmudkip/DSC00594.jpg)
beautiful
I don't have any pictures of mine but I made a very simple one by taking a piece of cord and splicing one end into a loop (take one end a feed back into itself) then putting a monkey's paw at the other end that is just barely small enough to fit through the loop I made. I just leave it looped through a hook on my belt and then open it up, put the handle of my mug in, and push the monkey's paw through the loop. It works pretty well.
I tied a piece of hemp twine to my handle (bowline, of course), and tied a bowline in the other end. About 18" of twine. When I'm drinking, I loop the free bowline back on itself to make a slip knot, which I put onto my wrist. I never lose my cup, no matter how many I've had.
When I secure it on my belt, I slip the free bowline under my belt, pass some of the twine through the bowline, and then the cup through that loop. The cup is so light, I can just tuck the excess twine behind my belt and it stays.