Discussion with info on the Machine Tool font and using single-line fonts in Rhino.
Some are available in different formats, including single and double line.
Examples of using Lettering Delights' "thin fonts" with Make-the-cut software.Unfortunately, they seem unique to that software and nothing else will open them. Lots of "thin fonts" (to buy) for use with Make-the-cut software.More on removing double lines with Inkscape.Has various Inkscape scripts for removing double lines.
closed fonts, how to remove double lines in Inkscape. There's a "pro" version which has extra editing capabilities. The fonts appear similar to Machine Tool or Hershey. A free font pack is available which adds extra fonts. The free version has basic tools to set size, spacing, angle, curve etc. It will generate either a DXF file or G-code toolpath for whatever text you enter.
You could raster a normal font (shading in the black areas) but this would take time. For example, suppose you have a laser cutter and want to mark text on something. Single-line fonts (also called engraving fonts, technical lettering fonts, pen plotter fonts) are hugely useful when performing machining or drawing operations. In addition to the Hershey extension, they have an excellent overview of what exactly a single-line font is and how it compares to "outline" fonts. Go and read Evilmadscientist's page on their Hershey text extension for Inkscape. Summary of single-line fonts (10/01/15) What's a single-line font?