Impressive indeed. Making a complete font set can easily take as long as a year. The tasks include to go from 'A' to 'Z', upper and lower case, plus all the glyphs (brackets, ampersand, exclamation marks etc). Optionally the variations (bold, italic etc) without which a font is of limited use. The thing that separates the men from the boys is the kerning (spacing between the characters) which can absorb as much obsessive compulsion as you can throw at it. From TFA:
> My new fonts were going to support 176 characters, meaning I might have to enter as many as 176² = 37,976 kerning pairs... yeah not going to happen. So this time, since I was (spoiler alert) writing my own tool to generate the fonts, I decided to semi-automate this process to take care of a huge majority of the kerning, and do manual entry when algorithm didn't suffice.
> My new fonts were going to support 176 characters, meaning I might have to enter as many as 176² = 37,976 kerning pairs... yeah not going to happen. So this time, since I was (spoiler alert) writing my own tool to generate the fonts, I decided to semi-automate this process to take care of a huge majority of the kerning, and do manual entry when algorithm didn't suffice.