Verdigris is basically copper acetate, an ancient easy to make pigment used for green in the Book of Kells and other insular manuscripts. Interestingly the brightness of the green in Kells suggests distilled vinegar was used but it was made several hundred years before distilation was known in Britain.
First soak some copper in vinegar, malt vinegar works but distilled gives a more turqiouse green. Then just leave it for a week or so at room temperature.
Once its green pour out in a shallow bowl and allow to evaporate before scraping up the residue and grinding it to powder.
For best results grind it with gypsum and use egg glair to bind.