Micro Magnets (100/pkg.), Neodymium Magnets: Educational Innovations, Inc.
500pcs Tiny Mini Magnetic Magnets 1x0.5 mm Small Round Micro Ndfeb Imanes Diameter 1mm x 0.5mm Neodymium Disc Sensor Mini 1*0.5 - AliExpress Home Improvement
MicroMagnets by Zen Magnets – 2.5mm Neo Sphere Rare Earth Magnets (Neoballs) that don't suck