I am an artist who uses recycled/reclaimed/rescued supplies. I was 'Green' before the first official Earth Day!
This Instructable is my first (of hopefully many), so please be gentle...

Tape core bangle bracelets have been around for ages but most people find them to be waaaaay too big (fig. 1) so I played with a few until I discovered an easy way to turn them into cuff bracelets (fig. 2). I will show you how to make an empty tape core into a fabulous original work of wearable art. If you decide these simple instructions are beyond your skills you can always see more finished recycled odd art and curious crafts at http://www.oddartist.com

Step 1: Step A

Things you will need:
        - Empty tape core - these come in many widths from your basic 3/4 inch painters tape to the wider packing tape roll that I prefer to use.
        - Scissors
        - Gesso/primer
        - Paint or anything else you care to decorate your cuff with
        - Clear coating (spray or brush-on)

Begin with making certain there is no adhesive or residue on the core. Do this by running your fingers over the cardboard. If it's sticky, just rub the spot with your thumb until the residue rolls off.
Find the outer seam. You want to cut that section out using the places the seam touches the edge of the core as your guide. This will give you the proper size. If you need it larger just leave a little more of the seam since you'll be rounding the corners anyhow.
Carefully round the edges of your cuff with the scissors. It doesn't have to be perfect but the cleaner job you do here saves time sanding later.
You can use the discarded piece as the base for a barrette - the arc fits a standard ponytail clip!

Step 2: Step 2

Fill a container with plain water. Dunk the tape core into the water so it is fully submerged for just a second or two. Set it aside to drain for a moment while the water is absorbed.
Now, using your fingers to support the core, gently roll the sides into a smaller circle. Try not to cause the core to buckle, you just want to gently shape the core. Work on one side, then the other, alternating until you get the shape you want. The core will warp a bit due to the way it's manufactured so gently twist the core the opposite direction until the warp is removed.
Wrap a band around the core to hold the shape while it dries.

Step 3: The Other Step

Once your cuff has dried you can lightly sand the rough spots and apply a couple coats of gesso or primer. This will stiffen the core and give you a nice blank canvas for your paint. Now paint away and let it dry. When your design is complete put a good coat of protective clear-coat to make your art last a very long time.
If you don't paint, try decoupage, cover with oven-bake clay or simply glue broken jewelry all over it.
How about hot-gluing globs or designs onto the cuff, glue crumpled tissue paper over it, or use just the BEST parts of recycled romance novels to make your own Naughty Bits*. Go crazy!

* You'll find my Original Naughty Bits as well as some of the cuffs I have made, along with all kinds of other odd art and curious crafts made from recycled supplies at http://oddartist.com