Golfsmith Putter Shaft Altering Tool:

The Putter Shaft Altering Tool allows you to alter lie angle and face angle on curved shafts. Perform quick and easy custom alterations of putters built with double- or single-bend shafts. Curved shaft putters cannot be altered for lie or to make the face sit absolutely square unless the shaft is bent. Although this tool does not make a curved shaft from a straight shaft, it permits lie angle and face angle changes to putter shafts.

Mounts in a bench vise — just put the shaft between the rollers for custom bends, whether the shaft is behind or in front of the clubface.