There is much software to make fonts. But I am not familiar with them and skilled in using them, and don't know which might be particularly good.
One example is the GNU licensed open-source software
FontForge 
. I used it to make the font which just shows the zero-whitespace character in the version history, which only has a symbol defined for this one character, looking like "|". The browser then automatically uses the next fall-back font for all other characters which don't have a definition included in that font.
In general, on just about all modern operating systems, on phones and computers, since at least 5 years or so, Unicode fonts for all kinds of international alphabets are included by default, and generally used automatically in browsers if any other font is specified which does not include a certain symbol by itself.
