Make your own ferrofluid in 5 minutes

Step 4 Play with it!

Grab your favorite permanent magnet and hold it up to the mixing cup (don't touch ithe fluid with the magnet, or even get close, unless you enjoy cleaning). Watch how the fluid turns from liquid to solid as you bring the magnet closer. Show your friends the horrible oily liquid you have in a cup, and then simulatenously slap a magnet onto it as you harmlessly 'dump' the cup over their heads (practice this first). Buy some cheap solenoids from http://www.allelectronics.com and electrically change the consistency of the fluid. Just enjoy!