A farthing wheel is a tool for producing a curved line in tooling, much like a small and variable fillet. A farthing wheel can be used for both blind and gold tooling. It consists of a brass wheel, mounted on a brass shank set into a wooden handle. The rim of the wheel is filed down to produce a line of a given width.

  ___
 / _ \              \ brass wheel approximately
| <o\ |             | 2.5 cm / 1 inch in diameter
 \_\ \              / (the size of a farthing)
    | |             \
    | |             |
    | |             |
    | |             | brass shaft
    | |             | approximately
    | |             | 10 cm / 4 inches long
    | |             | 5 mm / 1/4 inch in diameter
    | |             |
    | |             |
    | |             |
    | |             |
    | |             |
   /___\            /
  |     |           \
  |     |           |
  |     |           | wooden handle
  |     |           | approximately
  |     |           | 30 cm / 12 inches long
  |     |           | 10 mm / 1/2 inch in diameter
  |     |           |
  |     |           V

As with any tooling, tooling using a farthing wheel done by heating it up and impressing the design in (usually) leather. A farthing wheel is generally used on the cover of a fine binding, but not the spine.

Unlike those created by a fillet or roll, lines made with a farthing wheel are generally fine enough to end by simply lifting it off the leather. Overstamping is rarely required.