I actually made something similar a few years ago. I went to a surplus store and bought a length of backpack strap with a friction lock on the end, cut to a reasonable length. I use it as a belt almost every day.
The one on cool tools looks kind of nice. I might ... ahem ... buy it.
I submitted "MicroMuff" (a small windmuff for DSLR cameras) and they now list it. http://micromuff.com/
(Micromuff was created by a friend of mine).