A simple tool from an old open-end wrench compares favorably with a standard factory die with its versatility. If you work with bolts of different diameters and thread pitch, then you can use one tool to restore them, rather than a large set of different lehrs. Another plus is that you do not need to use the holder, as on a factory tool.
With this device, you can clean the thread of the old bolt from rust and dirt, and everything to create such a tool can be found in any garage.