The Thinker is a ferrofluid display that was funded on kickstarter. It comes in black, gold, and blue colored ferrofluid. It's 120 mL in volume with a magnetized bolt in the center to keep the ferrofluid spikey. The bottle is made of plastic so you don't have to worry about broken glass. It's also friction fit sealed, so you don't have to worry about the contents getting out and making a mess.