PS: This is my first instructable, so if you have any questions or anything isn't clear enough, let me know. The model isn't me, but rather someone who was nice enough to let me shoot him for this, so be nice or STFU. Thank you. :)
Step 1: Get It Together
1. Basic knowledge of sewing + a sewing machine/black thread. You could sew this by hand, but it'll take forever...
2. Old black jeans you don't want anymore, or a scrap of similar fabric
3. A few inches of black Velcro
4. Your choice of pronged studs, be they pointy or rhinestoned. I got mine cheap(about $3 for a bag of 100) from Spikes and Leather. You'll definitely have extras. It's okay. You'll put them all over everything, trust me.
5. Needle-nosed pliers(or any pliers, 'cause I couldn't find them when I made this a second time), or especially tough fingernails, if you're really punk rock and you're not against bleeding all over it. No really, just use pliers...
Step 2: Sew It
2. Get your fabric and cut it about 2 inches wide, and 2 inches longer than you measured.
3. Fold the fabric in half length-wise and sew the ends together.
4. Press flat with seam straight down the middle. Sew the edges of the collar to make it stay flat.
5. Hem the ends. Cut the Velcro to fit into that extra inch on either side. Sew it on, placing the rough side on the inside of the collar, and the soft side outside so they line up when put together. If you like the idea of a plain black collar, you could stop now. If not, proceed to...
Step 3: Stud It
You're done! Got more fabric left over? Follow the steps again to make a matching bracelet. Allergic to the metal studs? Cover the prongs with clear nail polish. Wear it, or give it to the bad ass in your life. Feel smug when people ask where you got it.