The oxidation state of the iron doesn't matter too much; I am just trying to make an attractive red-brown ink. Here are some instructions I prescribed to a friend.
Here's an approximately decent iron acetate recipe. I don't know if it'll work, though. Maybe you'll want to heat the acetic acid. The optional first step is to oxidize the iron by hydrogen peroxide or by heating in air. Pour enough heated acid to corrode the iron plenty. Wait. Filter what is now the aqueous solution of iron acetate and acetic acid through some filter paper to remove the undissolved iron. Let the (I hope so) red-brown solution dry: this is because you want to evaporate the acetic acid. When it is dry, you may dissolve what I hope to be a dark red-brown powder in as little distilled water as possible and some alcohol if you so desire. Adjust dilution to suit your hue/shading preference.
Would this synthesize iron (I or preferably II) acetate?