We have designed FontMixer as a free—and quite experimental—companion tool for IndyFont users, but it can be used in any circumstance where you would like to merge two existing fonts into a single entity—known in InDesign as a composite font.

The process is quite simple. You specify a “Base Font” which is supposed to provide your main reservoir of characters, say the basic ASCII set. Then you specify an “Extra Font” that contains additional characters or symbols. What is important here is that you have to supply the exhaustive list of characters which must be retrieved from this Extra Font. Enter a name for the composite font to be created, click the “Mix” button and you're done!

Example — Extending Charlemagne Std

Let's experiment FontMixer. As you know Charlemagne Std renders every letter in uppercase form. What we want is to create a composite font CharlemagneExt that will provide separate lowercase characters, gracefully integrated into the existing typeface. For this demonstration I have used IndyFont to instantly generate a fake extra font (Charlemagne Small) based in fact on a set of Bodoni sample outlines.

Here is the FontMixer dialog—click the screenshot for more details:

Run FontMixer, specify a composite font name, then select the fonts to be mixed.

Just enter the name of the composite font to be created in the “Font name” field, then select the Base font and the Extra font in the corresponding dropdown lists. Finally, enter the set of characters to be substituted in the “Characters” field. This will activate the “Mix” button.

Result in InDesign:

A fresh composite font has been created!

As you can see, when the composite font is selected the Glyphs panel displays the entire glyph set, including both the original uppercase letters from Charlemagne Std and the lowercase letters imported from my custom Charlemagne Small font. From then, CharlemagneExt behaves as a single font, which can be registered either at the application level or at the active document level.

FontMixer also allows you to easily refine or remove your composite fonts. Just rerun the script to manage them.

Disclaimer. — Composite fonts are available in the scripting DOM subsystem in InDesign CS5 and later. However, as they are intended to specifically address CJK typography features, they are not exposed in the GUI of the regular versions of InDesign. (More details on this obscure topic are available in the World Tools Pro manual, great plug-in from In-Tools by the way.) Therefore, FontMixer must be considered a kind of hack, and used with caution.

• See also: Introductory example, including a code snippet that reveals the trick behind FontMixer (InDesign forum)