Read Brad Thomas Parsons's "Bitters" today. It's more a recipe book than a historical record, but it feels like a valuable reference for that nagging feeling I have that I'll be making my own bitters sooner rather than later.
What strikes me about DIY bitters, however, is that any recipe I develop that requires my own bitters will then require that I carry said bitters with me. There's something to be said for being able to recreate a cocktail in someone else's bar with the ingredients in said bar when called upon.
I like the suggestion in the book of holding a "bitters making party" where you and your guests pool resources to create batches of bitters and then reconvene a month or so later to compare results. That's an idea I can get behind.