Relief SingleLine CAD is a sans-serif by François Chastanet, Noëlie Dayma and Élisa Garzelli, and the name is literal about it: single-line letterforms drawn with CAD output in mind. It comes from the type program at institut supérieur des arts et du design Toulouse (isdaT), which publishes its typefaces as open source and keeps the sources on GitHub. The file here is the Regular, one weight, nothing else to pick from.

A single-line sans has a narrower job than a display face. Pen plotter line art sits at the top of the list, closely followed by lettering sent to a CNC router for engraved aluminium shop tags. It also reads cleanly as callout text and room labels inside architectural floor plan drawings, the kind of annotation layer that gets printed small. Laser-etched control panel legends are another honest fit. Coverage runs past 293 Latin-based languages, so French accents and Central European diacritics hold up across multilingual drawing sets.

Pair it with a heavier grotesque for titles and leave the small annotation text to this one; the contrast between a filled headline and a thin single-line label does most of the hierarchy work on a technical sheet. Having the sources in a public repository also means you can open the glyphs and check how they are built before committing to it on a job. The font is open licensed under the OFL, free to use in personal and commercial work, and the files download directly from this page.