It's easy to make a working stylus for your tablet or mobile device with just a few household supplies, including an ink pen and cotton swab.

Researchers at OIST built a graphite disk that levitates and spins for hours in a vacuum, showing how perfect magnetic symmetry can cancel energy loss.

When buying a ratchet and socket set, you may have noticed a small plastic disc that comes with the kit. This does have a very functional purpose.