Ferrofluid is a lot of fun to play around with. Most people usually do it manually with a strong magnet. It is also possible to use magnetic fluid in a speaker and have it dance to the beat of your music. Take this Bluetooth 5.1 Ferrofluid Speaker for instance. It has a 50W subwoofer and offers 360-degree stereo sound.
This ferrofluid speaker has a range of up 80ft. It lasts up to 12 hours on battery (6000mAh). It has a solid wood outer shell and bunch of buttons and knobs for adjusting volume changing song, locking the magnetic fluid, and changing its shape.