Source: YouTube
These tiny magnets are only 2.5mm in diameter but their creative capabilities are huge. Pull them into a chain, fold them into a fabric, and meld them into limitless shapes: both abstract and geometric, flat or 3D. It's great for massaging your mind, practicing patience, or relieving boredom. The magnets are 30 times stronger than those on a fridge and come in two sets of 432 and 1728 pieces for $25 and $85. Each kit also comes with a construction guide to kickstart your magnet building career. But they may not be suitable for small kids who can easily swallow them.