A scribe is a giant compass that draws circles on the ice. You can use one to draw your circles before skating your figures or to check your work after you’ve done them. They’re no longer common in stores, but they are still available.
Scott Irvine makes and sells custom scribes.
Figure 8 Boutique has some. Search for “scribe.”
You can also try eBay.
For general information on equipment, see the base post.