Bottle Bracelet.

You can use a utility knife or even a sharp kitchen knife to poke through the side of your bottle. (Be very careful with this! Make sure the bottle is on a stable surface, and anchor it so it want roll or jump.)
Using the slit you’ve just made as your starting point, cut all the way around the bottle, using one of those ridges as your guide. Scissors will work fine for this - use the big, tough ones you keep around for the heftier cutting jobs.

Now, make a perpendicular cut (see the blue arrow above). Then choose another ridge to cut along - based on how wide you want your finished cuff to be. Cut around the bottle again.

Great! You now have a rough bracelet. You’ll want to trim about 1/4″ to 1/2″ off of each end, so there’s a little gap in the middle. You’ll also want to round off the ends. I used a circle template and traced it with a Sharpie, but you can also trim the ends free-hand.

Now, cut two strips of felt. They should be a little longer than your plastic form, and about 1/4″ wider. Decide at this point how you want to decorate your bracelet. There are lots of possibilities here - you can do felt applique, or bead embroidery, or regular embroidery, or silkscreen, or stencils . . . .

Do all your embellishment on one of the felt pieces. I recommend keeping about 1/2″ of felt at each end of this strip unadorned, because you may want to trim it off later. (I didn’t do that here, and it came back to bite me . . . .)
Now, put your two pieces of felt together, right sides out. Begin joining them with a whipstitch along one of the long edges. Stop stitching when you reach the rounded end. (By the way, futuregirl has the best tutorial ever on how to stitch felt.)

Insert your plastic form into the felt, and adjust the felt as necessary so it lies smoothly against the plastic. Wiggle the plastic form a bit so that you have a roughly equal amount of felt at each of the rounded ends of the bracelet. Now, you might need to trim a little felt away from the ends, so that you have about 1/8″ sticking out beyond the plastic form.

After that, continue your whip-stitching until you’ve stitched the felt together completely.