I did this all summer long. Some bracelets I got the ideas off of Craftgawker, and others I just plain made up. This one, (shown in blue above) is made up. Here is how to do it-
1. Cut a line of hemp that is three times as long as the length you want your bracelet around your wrist. Pick 2 or 3 colors of embroidery floss and cut them 2 ft long. fold in half, so the loop of hemp becomes the top (and later to be the button hole) and make sure the embroidery floss is even. Tie a knot at the top, and make sure it fits around your button.
2. Keeping the hemp lines parallel, weave the embroidery floss in and out, from one side around to the other. You'll feel like you are braiding, except not- because you are weaving the floss around the stationary hemp lines.
3. As you go, squish the thread up so the hemp is covered, and keep going.
4. When you get to the length you desire, tie the bottom in a knot, then snip the ends of the embroidery. Then, thread the hemp through your button, knot, and cut. Now your bracelet is removable. And you are quite finished.
note- some of the bracelets on my wrist above, I didn't squish the thread on, and left the hemp visible. Just for contrast.