Advanced Tips: The Basics of Creating a Single-Line Font!

The Basics of Creating a Single-Line Font


I’ve been asked by a few folks for some tips on how to make single-line fonts, so I figured I’d put together a blog post with some basics.  A few notes before we begin:


🡺 Single-line fonts are not the same as outline fonts.  They are meant to be used with a stylus-type tool, such as sketch pens, engraving tools, embossing tips, foil heat tips for plotters, and similar drawing instruments.  These aren’t meant for print, nor for cutting out of vinyl, paper, or similar materials.

🡺 This guide is for designers who are already experienced with making “regular” (outline) fonts.  You should have a firm grasp of font-building basics before digging into these more complicated builds!

🡺 This guide is for PC users who build in Font Creator.  I know that other font making programs can also do this, but Font Creator is where I build.

🡺 This is in no way a detailed guide; there are a lot of things you’ll need to know how to do already that I won’t cover.


And a separate set of legal notes:


🡺 Yes, you can make a single-line font based on one of your own outline fonts.  But DO NOT make a single-line version of a font made by another creator, unless you have received explicit permission in writing from that creator to create a new version of their work.  A single-line version would be a “derivative work,” which is not allowed under most font licenses.

🡺 This also goes for free fonts!  Many free fonts are distributed under the SIL Open Font License (SIL OFL). While the SIL OFL allows you to make a modified version of a free font, it also requires that any modified versions you make are accompanied by that very same SIL OFL document.  So basically, you can make a modified version of a font that was released under the SIL OFL, but you can’t sell it! You have to give it away under that exact same SIL OFL.


All right!  Now that we have all that out of the way, let’s talk about how to start building these things.


You can either create a new project file, or you can take one of your own existing outline fonts and built a single-line version from it.  Whichever way you go, you’ll want to have some shapes in a few of the character spots so that you can make sure you’ve switched from outline to single-line mode correctly.


Single-Line Font Basics: Placeholder Shapes


If you’re using one of your own fonts as a base, open up your project file, rename it, and save it right away under a new name. (I usually just add “Sketch” or “Line” to the end of the name.)  This is mainly so you don’t accidentally save your sketch version over the top of your work file for the original outline font.


If you’re starting with a new empty document, just throw a few shapes into some of the character spots, like the triangle, rectangle, and oval I’ve put here in the A, B, and C spots.


Single-Line Font Basics: Enable Open Contours


In order to put Font Creator into single-stroke mode, you’ll need to switch on the ability to build single-line designs in TWO places.  First, go to the Tools tab in your top menu.  Select “Options” at the bottom to get the pop-up Options panel. In that panel, go to the “Font” tab, and tick the box next to “Enable open contours (design time only)”.


Single-Line Font Basics: Adjust Export Settings


Next, go to the File tab in the top menu, and click on “Export Settings.”  Once the Font Export Settings panel pops up, go to the drop-down at the bottom next to “Open Contours” and change it from “Close” to “Single Stroke.”


If you’ve done those two steps right, you’ll see a difference in your placeholder shapes or the letters of your font:


Single-Line Font Basics: Change to Single Stroke


All of your characters in the grid will change from solid filled shapes to outlines!  When you see this, you’ll know that you’ve successfully converted your project file from outline to single-stroke construction.


Single-Line Font Basics: Change to Single Stroke


When you go into a specific character’s build window, you’ll see the same change – with an outline font, it’s an outline filled with a solid color.  When you go into single-stroke construction mode, the outline color appears as a wider stroke around your construction strokes.


Some of you Font Creator users might be wondering right about now, why are my characters filled with gray instead of black?  Black is the default fill color, but it’s too intense for my eyes.  Here’s how to change it:


Single-Line Font Basics: Adjust Fill Opacity


Click on the “Fill Outlines” button in the top section – it’s two triangles, gray and white, with a diagonal slash between them.  You’ll get this option menu.  The default is “Solid,” but I like to knock it all the way down to 20% Opacity.  It’s dark enough that you can always tell where your fills are, but not so dark that it’s hard to look at.


Now that we’ve converted the working file to single-stroke construction, let’s dig in to see how the letters themselves are built!


Single-Line Font Basics: First and Last Points


Here’s the plain oval that I made in the letter C spot.  (I’ve tilted it 90 degrees just so my screenshot isn’t gigantically tall.)


The first thing to do is find your first point and last point.  And if they aren’t already, both points need to be nodes, not handles.  Their identifying markers will vary by program, but in Font Creator, the first point is the little green arrow pointing left at a solid line, and the last point is the little red arrow pointing right at a solid line.


If you find that either your first or last point is a handle (as my last point is, in the image above), you can either delete the handle, or add in a node.  You want to arrange things so that you have two nodes next to each other, with no handles in between.


Single-Line Font Basics: Set New First Point


Here I’ve added in a new node just above my first point, so that I have two nodes next to each other, with no handles between them.  In order to have one node be the first point, and the other node be the last point, I need to make the top node the first point.


To do that, right-click on the node, and select “First Point” from the menu that pops up.


Single-Line Font Basics: Toggle Open Contours


You can see that my first point is now a full node, and the last point is also a full node, with nothing in between them.  Now you can break this stroke open between those nodes!


Right-click anywhere on the stroke, and select “Toggle Open Contour(s)” from the pop-up menu.


Single-Line Font Basics: Open Contour


If you’ve done all of the previous steps correctly, you should now have an empty gap where there was once a piece of the stroke connecting the last point back to the first!


You’ll end up with a single stroke, starting at the first point, and ending at the last point.


Now you can shape this stroke into any letters you like.  You can add more nodes along the stroke if you need more corners, twists, and turns.


Single-Line Font Basics: Constructing New Letter


When constructing your letters, as with regular outline fonts, be sure to have points at all of the extrema, and keep your outlines as clean as possible.


If you’re making a traditionally open shape, like the C on the left, you don’t need to do anything special; but if you’re making a traditionally closed shape like the D on the right, be sure that you don’t connect the first and last points.  Leave a tiny gap.


Why?  Because if you accidentally close a shape, after you export the font, that letter just won’t appear when you go to use the font.  The font will be specifically looking for open strokes that don’t connect, and it’ll ignore any fully closed shapes included in the font file.


Single-Line Font Basics: No Closed Shapes


Here’s a close-up of two small circles.  Always construct like the one on the left; those two end points need to be separate. (I turned off the green and red arrows showing First Point and Last Point for this screenshot, because they were making this hard to see.)  Don’t complete the shape like the one on the right.


If you have nodes very close together like this, be very careful if you run the Validator or if you use the Optimize Contours button.  If you do either of those, Font Creator may close the outline for you.


This is why you should be building with extrema points and clean contours as you go; if you’re building optimized contours already, you don’t need to run the Optimize Contours wizard, and as such, you don’t run the risk of having your outlines close up!


Font Creator will also try to close up your outlines at every opportunity. It can’t help itself; it wants all outlines to be closed.  So pay extra careful attention when using tools like Rotation, Mirror, or Skew; you may need to perform these moves by hand, or do them and then go back and adjust your first point and last point, then do the “Toggle Open Contour(s)” again to get your stroke to break apart again afterward.  This may even happen when you copy and paste a stroke from one character slot to another, so always keep an eye out!


Single-Line Font Basics: No Two Point Strokes


Here’s another thing you can’t do:  Don’t make a single stroke with only two end points, with no handles or additional nodes in between.


Every stroke, even a single straight line, should have at least one other node (top line) or handle (middle line) somewhere along its length.  If it doesn’t, many program just can’t see that stroke.  (Just like they can’t see a fully closed outline.)


If you accidentally make a stroke like the bottom one, no worries!  Just select it by drawing a box around it with your selector tool, then delete it and create a new stroke with a curve or extra node on it.  While you can still select the end points and move them around, you won’t be able to click on the stroke to add a new node, or click/pull to curve the line.  Once it gets to this two-point state, the stroke is broken and can’t be repaired.


Single-Line Font Basics: Built from Existing Letters


Now, let’s talk about building a single-line version of one of your existing fonts.

Remember, and I cannot stress this enough: only do this with your own fonts. Do not do this with fonts made by other creators.


Here you can see the four parts:


[1] The original outline version of the letter D (this one is from my font “Succulent”).

[2] That same D, after the project file has been switched from outline mode to single-stroke mode.

[3] I’ve taken a couple of single-stroke lines and placed them inside the D shape, roughly down the middles of the original strokes.  I’m trying to replicate the size, shape, and curves of the letter.

[4] And finally, I’ve deleted the two original closed shapes (the outside outline, and the inner counter outline) so that I’m just left with my new version made from two single-line strokes.


You may wonder: instead of putting new strokes in there and deleting out the old letter, can you take the old letter, move its first/last points, toggle open contours, and then use that?  Yes, but.


I prefer the way I’ve done it above for a couple of reasons.  One: I like to keep the original shape there as a reference, so I can try to match its curves and angles as I build. Two: if you just use the outer outline, your letter might come out too wide, too tall, or too funky.  And three, the most important: this way is SO MUCH faster and easier.  But you can absolutely give both ways a try, to see what you like the best, and what works best for your particular outline fonts.


Single-Line Font Basics: Include Alternates and Ligatures


If you’re wondering if you can include all of the same elements that you’d put in an outline font, YES!  You can!  You can adjust kerning, add alternates, make ligatures, and include all of the same bonus features that you’d include in an outline font.  (But of course, you’ll make sure your side bearings are set perfectly before you even think about kerning, right?)


Up above, you can see a snippet of the character grid for Dear Agatha; I included alternates, ligatures, flourishes, and several other extras.  Dear Agatha is a single-line font I built from scratch; it isn’t based on an existing outline font.  It has 230 items in the Private Use Area, because I tend to go a little overboard.  If you’re just starting out, I recommend maybe not including so many extras.


Single-Line Font Basics: Export Options


Let’s now skip over days or weeks of work that you’ll be doing on your own. 😄 When you’re done building the font, it’s time to export!  You have two options, and I recommend using both.


You’ll want to use the “Export Font As” option, and in the “Open Contours” drop-down, there are two options: “Single Stroke” and “Double Stroke.”


The Single Stroke version is a true single-line font; the Double Stroke version takes your single strokes and turns them into outlines, basically going from the first point to the last point, then turning around and going back from the last point to the first point.  But it makes the outlines impossibly thin. Thinner than you could ever make by hand.


Here’s the weird thing: most programs that can use single-line fonts?  Can’t actually use Single Stroke fonts.  Cricut Design Space, Silhouette Studio, Adobe Illustrator, and many others actually need the Double Stroke version. I’ve found a couple of programs that can use the true Single Stroke version (Rhinoceros and EngraveLab); they’re CAD/CAM programs for use with specialty equipment, and they’re really expensive.  For most crafting programs, Double Stroke is the only choice.


Single-Line Font Basics: Preview of Single Stroke


This is the Windows Font Viewer preview of Dear Agatha, exported as “Single Stroke.”  It’s doing what most other programs will also do: it doesn’t understand the Single Stroke version, so it assumes the open-ended contours are a mistake.  As a helpful favor to you, it connects the first point to the last point with a straight line.  Then it fills in all enclosed areas.


Meanwhile, if we look at the “Double Stroke” version of the same font:


Single-Line Font Basics: Preview of Double Stroke


Most parts of the strokes are so super-thin, you can barely see them.  (Some curves may get a tiny bit darker; that’s totally OK, it’s due to how Windows is struggling to show outlines that are so thin.)


So, you may ask, why do you want to make both?  Why even bother exporting the “Single Stroke” version, if so few programs can actually use it?  Why not only make the “Double Stroke” version?


The main reason is that some programs can use the Single Stroke version.  There’s no reason to alienate that group of customers, when it’s so easy to include them.  But also, while Windows here figured out how to show these whisper-thin outlines, some programs and operating systems haven’t figured out how to do it.  So they just … don’t show anything at all.


Single-Line Font Basics: Invisible Fonts in iOS


Here’s an example: I’ve installed the Double Stroke version of my font “Muggsy Sketch” to an iPad.  The iOS is terrible at displaying these fonts.  On the left, you can see the blank space where Muggsy Sketch lives in the AnyFont app.  (I actually had two versions in there, while I was doing some testing.  So between Ludicrous and Pinsetter, you can’t see Muggsy Sketch and Muggsy Sketch 2.) The font is there; the iPad just can’t show it because its lines are too thin.


Same thing on the right, inside the Cricut app; Muggsy Sketch is there, installed and ready to use, alphabetically between Mishafi and Myanmar Sangam MN.  But the iPad can’t show it.


(The images above and below came from my article about how to install and use single-line fonts on an iOS device, since this invisible weirdness definitely needs some guidance!)


Single-Line Font Basics: Double Stroke version in Cricut App


When you choose that “invisible” font and type with it in the Cricut app, it shows up because Cricut automatically puts a fine black stroke around all typed text.


A great reason to make the true Single Stroke version—even though it isn’t useable for design creation in most programs—is so that you have a version of the font that people can SEE.  If someone is using Dear Agatha in Cricut Design Space, they’ll need to use a secondary program (like Font Book on a Mac, or Character Map on a PC) to grab those 230 alternates and ligatures.  But if that secondary program can’t show the super fine lines of the Double Stroke version, your customer won’t be able to find the letter they want.


What I usually recommend to customers is to install the Single Stroke version too, and go look up THAT font in Font Book or any other secondary program.  As long as you have the same Unicode name for each alternate/ligature in both the Single Stroke and Double Stroke versions, they can copy/paste the wonky, blocky version that they can see, then select it and change it to the other version that they can use.


Single-Line Font Basics: Are They Worth It?


Heck yeah, if you have the patience for both construction and support!


While these fonts are fussy and more difficult to build, this is also a category of fonts where very few are being made (see the aforementioned fussy/difficult issues), but the customer base is growing steadily.  People want to use them with sketch pens in their Cricut and Silhouette machines; or the We R Memory Keepers foil quill in those same machines.  They can be used for engraving and embossing, CNC, and laser machines like the Glowforge.


These definitely aren’t for everyone, though; they take far longer to make, and there are a ton of ways they can go wrong if you aren’t careful, which might leave you shaking your fist and shouting things like, “Why won’t the Q show up?!” But if you’re building clean, well-constructed single line fonts, there’s absolutely a market out there eagerly waiting for them!


Also, know going in that you’ll be asked for support and help for single-line fonts far more than any of your outline fonts, because they can be just as fussy and difficult to use as they are to make. (The darned things being invisible on iOS devices is just one of the many weird issues.)  I include a full PDF guide with all of mine, which covers a ton of information. You can check it out here; you won’t be able to include my PDF with your products, but you can test out your font in all of the same programs and construct a similar document for your customers.


I also strongly recommend enlisting friends and fans to test out your fonts, to make sure that all letters work as they should.  There are tons of folks out there who would be delighted to help test out a new font in exchange for a one-user commercial license!  (It’s thanks to my early testers that I figured out several of these tips, especially that you can’t have closed outlines, and you can’t have a stroke with only two points.)


And because it bears repeating one more time: DO NOT make single-line versions from someone else’s font.  (Have I hit that point hard enough?  I hope so!)  Create fresh ones from scratch, or make single-line versions of your own outline fonts, in order to avoid any legal issues.


Moderated comments are open on this post, if you have any questions!

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