Several ideas...
- Chip Clips
** Bonus if they are small and have pointy plastic Teeth!
- Paper Binders
** Smaller ones hurt a lot more, bigger hurt less, but still hurt like hell
- Skirt or Pants Hangers
** Bonus if you hang stuff from the hook
- Simple Bobby Pins right on the Nipple Buds
** Bobby pins such as are used in movies to pick locks, a.k.a. hair pins
** very easy, almost too easy for most
** for additional sensations, tease the nipples lightly with a vibrator
- Acupuncture Needles (Warning: possible blood and risk of infection if done wrong)
** Use the nipples as pincushins
- Birthday Candle Nipples (Warning: Risk of Burn Injury / Infection if done wrong)
** vertically pierce each nipple, take a birthday candle and place on the needle, light the candles, let the wax drip all over each nipple
- Alligator Clips
** Typically used with electronics to clamp onto exposed wires
- 9V Battery
** Get the nipple wet so moisture can conduct the charge
- Shock Collar
** Typically used for dog obedience, there are two small prongs that should touch on the side of each nipple
** MAJOR WARNING - NEVER RUN ELECTRICITY ACROSS THE CHEST - HEART ATTACK CAN OCCUR
NOTE: I know this thread is quite old and the OP probably wont reply. I posted mostly for putting out some additional ideas.