Tools and Materials:
Metal cone studs (mine are 1/2 inch) with screw
Flat-head screw driver
Jump ring and clasp
Oval link chain
I highly recommend buying your studs first, and having them in hand when you pick out chain. This way, you can make sure that the stud fits in the links. Cut chain to a length that fits around your wrist.
Take apart a stud, and place the screw side through one of oval links. Put a drop of glue in the stud's hole. Less is more--because you don't want it to get too messy. I recommend using the glue because otherwise you might end up with a few loose screws. (In more ways than one.)
Twist on the cone stud, and tighten with the screw driver.
Repeat for the other studs. The number of studs and their placement is up to you.
Add a clasp to the chain using a jump ring, and you're done!