You'll need: FontCreator (Windows and macOS), comfort drawing and selecting contours in the Glyph Edit window, and the engraving, cutting or CNC software you'll run the finished font in.
A capital A drawn as a single open centerline path in the Glyph Edit window — thin strokes, no fill — beside the Font Export Settings dialog showing Open Contours set to Single stroke.
A single-line font is one whose letters are drawn as centerlines — one thin path per stroke, with no thickness — so a CNC router, laser, vinyl cutter, or engraving tool can follow the line directly instead of tracing around a filled shape. Cutting and CNC programs such as Make The Cut, Sure Cuts a Lot, Rhino, Silhouette Studio, and Cricut Design Space can all drive designs from fonts, and a single-line font gives them the cleanest possible toolpath.
Here's the catch the format imposes: OpenType (and TrueType) fonts are fundamentally built from closed contours that enclose a filled area, so a true single-line OpenType font doesn't really exist. FontCreator works around this by letting you design and export open contours — paths whose start and end points are not joined — and by giving you two export modes that engraving software understands. This font editor is one of the few that makes the open-contour workflow practical end to end, on Windows and macOS alike.
Note: Single-line fonts are meant for engraving and CNC, not for normal text display. In ordinary apps they'll look unfilled, broken, or invisible — that's expected.
What an open contour is (and why engraving needs centerlines)
A normal glyph outline is a closed contour: the path returns to where it started and encloses a region the rasterizer fills with ink. When a cutting machine is handed a closed letter, it cuts around the shape — two edges per stroke — leaving a hollow outline of the letter, not a single engraved line.
An open contour is a path that simply stops at its last point. There's no enclosed area, so there's nothing to fill — what you see is the line itself. Run a tool along that line and you get one pass down the centerline of each stroke, which is exactly what engraving, scoring, single-line cutting, and pen-plotting want.
So the design rule for a single-line font is: draw each stroke as one open path down the middle of where the stroke should go, and leave it open. Not every glyph has to be open — a glyph like O or o is naturally a single closed loop and can stay closed — but the strokes you want engraved as lines must be open contours.
Turn on open-contour export (Single or Double Stroke)
Open contours only behave as single-line output if you tell FontCreator to export them as strokes. That switch lives in the export settings.
- Open File → Export and choose Desktop Font As (ttf/otf)….
- In the Font Export Settings dialog (Desktop tab), find the Open Contours option. It appears only when your font contains open contours, and the same option is on the Web tab too.
- Pick the export mode. The choices are Close, Exclude (recommended), Single stroke, and Double stroke — for single-line output you want one of the stroke modes:
- Single stroke — the most efficient: each open path is exported once, as a single line. Best for software that supports single-line/stick fonts. - Double stroke — reverses each path so it's traced out and back; most engraving machines follow this reliably. Choose it if Single stroke confuses your tool. - (Close joins each open path into a filled shape, and Exclude drops open contours from the export — neither is what you want for engraving.)
- Export, then open the result in your engraving/cutting software and run a short test cut on scrap before committing.
Open contours imply the TrueType outline format — the CFF (PostScript) format can't store them — so keep the export set to TrueType. And remember that even a correctly exported single-line font still renders oddly in normal text apps; that's the format's limitation, not a mistake on your end. Test both stroke modes with your specific machine and software; which one wins depends on the toolchain, not on FontCreator.
Tip: Once open contours are present, FontCreator shows contours as strokes rather than filled shapes in the Glyph Edit window, which makes designing single-line glyphs much easier to read.
The Font Export Settings dialog with the Open Contours dropdown expanded, showing Close, Exclude, Single stroke and Double stroke.
Draw a single-line glyph step by step
- Create a new font. Start a fresh project in FontCreator.
- Open a glyph in the Glyph Edit window (double-click it in the font overview).
- Draw the centerline. Use the Draw tool to place points down the middle of each stroke. Hold Shift while adding points for straight segments; drag the mouse to create curves.
- Insert extra contours as needed via Insert → Insert Contour, drawing each stroke as its own open path.
- Open an existing closed contour if you imported or built one that should be a line: select the contour and break it so its start and end points separate, leaving an open path you can refine.
- Repeat across your glyphs, keeping strokes open and only leaving naturally-closed loops (like
O) closed.
Drawing the centerline of a lowercase e as a single open path, with on-curve points along the centerline and no fill.
Watch out: Some cleanup tools assume closed, filled contours. Optimize Contours in particular may not behave well on open paths — adjust the first point and node positions manually where you need precision rather than relying on automatic optimization.
Single-line vs stroked (monoline) fonts — don't confuse them
This is the most common mix-up, so it's worth being explicit:
- A single-line font (this tutorial) keeps paths open and exports them as Single/Double Stroke so a tool follows the centerline. The output is a line, not a filled letter.
- A monoline / stroke font keeps a centerline too, but you give it a stroke width and FontCreator expands it into a normal filled closed outline. The output is a regular printable font.
If you want a font that prints with uniform-width strokes, that's the stroke workflow — see Designing with Strokes. If you want a font that cuts or engraves down the middle of each stroke, stay here and keep your contours open.
Tip: If you've drawn skeletons using the stroke feature but actually want single-line output, don't expand the strokes — instead design with plain open contours and use the Open Contours export setting. Stroking and single-line export are mutually exclusive intentions for the same path.
Save your work as a project
Save as a FontCreator project (.fcp) file. The project preserves your open-contour geometry and the export configuration (including the Single/Double Stroke choice), so you don't have to reconfigure each time you re-export.
Demo font for download
You can download a ready-made single-line project and exported fonts to inspect the workflow:
- SingleLine.fcp — the FontCreator project
- SingleStroke.ttf — exported with Single Stroke
- DoubleStroke.ttf — exported with Double Stroke
Open the project to see how the glyphs are built, and try the two TTFs in your engraving software to find which mode your toolchain prefers.
A note on color/SVG fonts
OpenType SVG outlines do support open paths, so if your target software reads OpenType-SVG color fonts you could in principle keep open contours there. In practice we're not aware of CNC or engraving tools that consume OpenType-SVG fonts — so for cutting and engraving, the Single/Double Stroke TTF route is the dependable one. If you find a tool that reads SVG single-line fonts, let us know.
Troubleshooting
| Symptom | Likely cause | Fix |
|---|---|---|
| Letters look filled / hollow outlines in the cutter | Exported with closed contours, not a stroke mode | Set Open Contours to Single stroke or Double stroke in Font Export Settings |
| The font looks broken or invisible in Word/browser | It's a single-line font, not for screen display | Expected — use it only in engraving/CNC software |
| Tool cuts each line twice or backtracks oddly | Double stroke chosen where Single stroke would do | Try Single stroke instead |
| Tool drops or skips some strokes | Single stroke not understood by that software | Switch to Double stroke |
| Optimize Contours mangles open paths | Cleanup tools assume closed contours | Skip Optimize; adjust the first point / nodes manually |
| Open Contours option missing from export | Font has no open contours yet | Draw open paths, or break a closed contour into an open one first |
Frequently asked questions
Can FontCreator make a true single-line OpenType font? Not literally — OpenType and TrueType are built on closed contours, so a true single-line OpenType font doesn't exist. FontCreator works around this by letting you draw open contours and export them with the Single stroke or Double stroke option, which engraving and CNC software can follow as centerlines.
What's the difference between Single stroke and Double stroke? Single stroke exports each open path once as a single line — the most efficient option. Double stroke reverses each path so it's traced out and back, which many engraving machines follow more reliably. Test both with your machine; the better choice depends on your software, not on FontCreator.
My single-line font looks broken in normal apps — did I do something wrong? No. Single-line fonts are designed for cutting, engraving and CNC software, not for screen or print. In ordinary applications they'll appear unfilled or incomplete because there's no enclosed area to fill. Use them only in the machine software they're made for.
How do I turn an existing closed letter into a single line? Open the glyph, select the closed contour, and break it so its start and end points separate into an open path; then redraw it as a single centerline if needed.
What to read next
- Designing with Strokes — the related but different workflow: design from a centerline skeleton, then stroke it into a normal filled font.
- Export a Font — full detail on the Open Contours export option and the rest of the Font Export Settings.
- Creating a Font and Editing Glyphs — drawing, the Draw tool, and contour editing basics.
