Small Ball Casters Heavy Duty Conveyor Roller Ball Casters4pcssilver | Fruugo ES
Ball Caster - 3/4 Metal Ball : ID 1200 : $4.95 : Adafruit Industries, Unique & fun DIY electronics and kits
Pololu Ball Caster with 3/8″ Plastic Ball
Metal ball casters - DFRobot
10pcs Miniature 8mm Robot Bearing Steel Ball Roller Ksm-8 Swivel Round Ball Caster Drop In Universal Small Ball Transfer Unit - Furniture Casters - AliExpress