UPDATE August 2020: The link to the store mentioned below is no longer working. If you’re looking for Spirograph replacement parts, try Etsy or eBay. Sometimes people sell individual pieces there. The vintage Spirograph sets are compatible with the new ones.
Are you missing a Spirograph wheel or gear? Did a key piece get broken? Did you buy an old second-hand set that’s short a few pieces? Are you wishing for more Super Spirograph parts to make different shapes?
Kahootz Toys, the makers of the new Spirograph, have set up a shop where you can order single Spirograph replacement parts.