This is how I built custom fonts for Ucglib/ Ucglib_Arduino on Linux.

Ucglib uses BDF fonts as a source. You will need:

• OTF and TTF files of the fonts you want to convert. Check licenses!
• A way to convert these to BDF format: otf2bdf , gbdfed, or possibly fontforge
• A way to convert BDF files to the C structures used in Ucglib: bdfconv, which you will build below.

Download the Ucglib repository, head into tools/font/bdfconv and

$ make

This will build a bdfconv executable. Put that executable or a symbolic link to it into your bin directory.

Using otf2bdf:

$ otf2bdf -v -n -r 72 -p 71 -l '32 48_57 65_90' -c M -o filename.bdf filename.otf

gbdfed also can import and convert fonts, but the monospace/proportional setting seems to be wonky. fontforge appears to be another option.

View the result using gbdfed.

$ bdfconv -v -b 2 -f 0 -n fontname -d image.tga -o filename.c filename.bdf 

Note: There seems to be an upper limit to the size of the font. What is it?

Paste the content of the new file to src/clib/ucg_pixel_font_data.c

Add an extern entry for the above to src/clib/ucg.h