HershTrans is a simple tool that will allow you to convert Hershey fonts from one format to another. One of these formats is SVG, allowing you to conveniently edit them.
Hershey fonts are an archaic plotter font format designed by the US National Institute of Standards and Technology. They're almost completely obsolete, but they're tiny, dead simple to draw, and are available under a very liberal license, which means they're still useful. HershTrans is a quick hack I put together when I suddenly needed to use them for something.
The program is MIT licensed.