Single line font, work-around


I’m trying to create a single line font using Fontself.

I know all standard font formats only supports closed path shapes and no open lines. But theoretically it should be possible to create a closed path drawn on top of itself to make it have no thickness at all, thus appearing like a single line font.

As you see in the image below, the character C is drawn using a line that closes the path by going back and forth on top of itself. This double line is revealed when moving one control point (the C to the right).

I know this is experimental usage and not the typical user case, so I’m not surprised that it does not work as I would like it to work.

However, when saving fonts, Fontself refuses to export any straight vertical or horizontal lines. My guess is that Fontself checks if an sAIPath object has 0 height or 0 width, and if that is the case Fontself just omits it. And not only omits it, it is also completely deleted in the Illustrator document.

My work-around for this is to move one of the ends of any straight line say 0.01 mm to make the path object have some “bounding box volume”. It works, and I have succesfully created my “single line” font.

But in a future version, it would be nice if I could save the font as is without Fontself omitting 0-thickness volumes.

Hello superpanic,
welcome to this forum.

In Fontself it is quite possible to create letters that consist of an open path.

I have created a small example of an open triangle with the path tool. No filling. Path thickness first 1 pt. I have assigned this to the “1” key.

How thin can it get?
I copied the open triangle and assigned it to the “0” key. At 0.1 pt path thickness, the letter is still displayed in the character set, e.g. at the size of 400pt. Illustrator rounds 0.001 pt to 0 pt and then you get an empty letter without a path.
See screenshot.

I have tested the created character set on Mac in AI and Textedit.

Hi urs7000!

Thank you for doing this experiment!

Unfortunately it is not quite what I am after if I understand your description correctly. Fontself translates open path outlines to filled polygons. And yes, it the outline can be made rather thin. But I would like to create a truly single line font for use in a laser cutter or a vinyl cutter. The open triangle you created will have either a double line (a thickness >0), or if the line is thinner than a certain threshold it is omitted by the parser and lost.

The best I could do is to draw a closed path over itself and not using any outline at all, just fill. This way I can create font shapes without any line thickness.

The way I do it now is not perfect, as the laser cutter will cut the same line twice back and forth. I can of course set the laser strength to half, but it will take longer time to cut …

And I also have to handle the problem where the Fontself parser deletes all single straight lines without thickness …

Thank you again for looking into this! And please let me know if you think I misinterpreted your explanation/experiment. :•)

Hey, just confirming that Fontself does not support single stroke fonts to avoid compatibility issues, and there is no workaround we are aware of.

I am also very interested in this style of font creation.
I have read that in other font software there is the option to turn of auto-closing and auto outlining of fonts and then users rename the file extension of an exported .ttf to .opf after the export using the settings above.
Sadly there appear to be only a couple of software programs that accept the .opf font format but I hope this expands.
Would this be a possibility for a future fontself update perhaps?

Have you tried exporting to Color SVG format?

Hello everybody. I have a complicated workflow that might be nonetheless interesting.

I create a ‘skelleton’ font in Illustrator. (Single line, as in the first picture).

I use FontSelf to create a font, but the font is black-and-white and the glyphs become ‘contoured’ (Strokes are converted to outlines by FontSelf).

I then use the CLI-application ‘fonts2svg’ ( to create SVG images from the glyphs in the OTF.

I copy this folder, and paste the glyphs from Illustrator here and remove the old contours. The new glyphs are single-line.

I then use the CLI-tool ‘addsvg’ to add the new ‘inline’ glyphs to the font. This creates a OTF/SVG font, with the single line glyphs as SVG. Illustrator, and other tools, will now display the SVG-images instead of the original glyphs.