Ferrofluid is a lot of fun to play around with. Most people use strong handheld magnets to interact with magnetic fluid toys. The Soulbeat Golden Ferrofluid Bluetooth 5.1 Speaker uses sound to make the fluid dance. It comes with a bunch of gorgeous buttons and knobs that let you adjust volume, shape of the fluid, and other settings.
This speaker system has a 50W subwoofer. Its battery lasts up to 8 hours (6000mAh). The Soulbeat Golden Ferrofluid Speaker has a compact design but is pretty heavy. You can find out more about it here.