Amazon.com: 80mm High Hardness Plastic Mecanum Wheel Omni-Directional Smart Robot Car Tire with Cross Type Hubs Compatible with Lego Blocks DIY STEM Toy(2 Left 2 Right) (4, 80mm) : Toys & Games
LEGO MOC Omni-wheel 4x4 by olivierz | Rebrickable - Build with LEGO
48mm Omniwheel (compatible with Lego Mindstorms NXT) - RobotShop