Above are two examples of chairmaker’s travishers. These specialized convex spokeshaves are used to create the final shape of a chair seat after it’s been roughed in with an adz and shaped with a scorp.
The Travisher on the left runs $120 at Highland Woodworking. It has a 3″ wide convex blade and handles which continue along the curve of the blade so you can cut into deep hollows. The one on the right is sold at Classic Hand Tools for £82 or $130. It has a 4.75″ radius and is designed to be pushed by your thumbs. It also has a slot in the top for shavings to exit.