Magnetic balls are kind of pricy and dangerous, but on video, you can enjoy them at someone else's expense. YouTuber Magnetic Games has lots of magnets: large, powerful magnets and thousands of magnetic balls. Watch him demonstrate their attraction to each other in slow motion.
I assure you that the impact between the Monolith and 2592 magnetic balls scared me. The collision of magnets was violent and the balls were splashed all over the room. I wore protective glasses at every impact, and it served.
The interaction between the magnets is fascinating and satisfying, but eventually you have to feel for the task ahead of sorting all those balls back into their colors. There are links to product pages for the larger magnets with specifications at the YouTube page. -via Laughing Squid