1. FontTools/TTX, which can convert a font into XML and back again.
However, Petr reports that it currently crashes on Open Sans[3], and we
have no smart way of verifying that the "To XML, patch, compile to TTF"
cycle produces a font that performs at least as well as the original.

The problem of embedding flags is now being addressed by the packaging of
a simple tool called "ttembed" which just touches OS/2.fsType and
checksums, nothing else.[4]

The proposed method would be to write a very simple recipe for the font
changes, like this:

recipe.txt:

  OS/2.fsType=0
  OS/2.panose=4,0,0,0,0,0,0,0,0,0
  name.1.0.0.1="Letters Laughing at Their Execution"
  name.1.0.0.2="Regular"
  name.1.0.0.4="Letters Laughing at Their Execution"
  name.3.1.1033.1="Letters Laughing at Their Execution"
  name.3.1.1033.2="Regular"
  name.3.1.1033.4="Letters Laughing at Their Execution"

and apply it with:

  $ ttpatch recipe.txt LettersLaughing.ttf