You can purchase various size Whip Finish Tools for Fly Tying, or you can make custom size ones that work well with larger fishing flies that have lots of things like hackle, feathers, and rubber legs that get in the way. Larger gap in the tool makes for easier whip finishing of foam grasshoppers and spiders where the final wraps are completed mid-body at times.
Purchase a Whip Finish Tool https://amzn.to/3WI71JX
Or, Make Your Own:
- K&S Piano Wire: https://amzn.to/3QPPxaA
- K7S Bras Tube: https://amzn.to/4c0WRsn
- Copper Bead: https://amzn.to/3V6zcRF