fontforge (an outline font editor)

FontForge is an outline font editor that lets you create your own
postscript, truetype, opentype, cid-keyed, multi-master, cff, svg and
bitmap (bdf, FON, NFNT) fonts, or edit existing ones. It also lets you
convert one format to another. FontForge has support for many Macintosh
font formats.

Optional dependency: Sphinx (for building documentation). Auto-detected.
You can export DOCS=no to skip building the docs if Sphinx is installed.