Amazon.com: Replacement Marbles for Marble Run - Set of 100 - Assorted Colors - Size 9/16 Inch (14mm) - 100% Glass : Toys & Games
Amazon.com: Multi-Colored 1/2" Chrome Steel Balls for GraviTrax Marble Run | 20 Pack | High-Visibility Steel Marble Set Great for Racing, Rolling & Games | Colored Marbles Compatible with Marble Runs &