Equal parts berry pits and skins left over from juicingand white wine or white vinegar
Combine the vinegar and berry pits/skin in a non-reactive container (I like a mason jar) and refrigerate for a month or two, shaking occasionally. Occasionally taste the vinegar to check on it's progress, when it's to your liking, strain it through a fine strainer or cheesecloth, pressing down on the skins and pits with a spoon or ladle to get as much vinegar as possible. If the vinegar is very cloudy, strain it again.
I should mention many wild berries and things I make this with need to be cooked to extract their juice. I do this by putting the cleaned berries in a stainless steel saucepan and adding water about 3/4 of the way up to the surface of the berries, then I heat them gently until their hot and have released their juice, pass them through a strainer or food mill, then reserve the pits/skins, and juice separately.Wild and cultivated grapes are my favorite for this, since they don't require cooking to release their juice, which yields a much more potent flavored vinegar. Both uncooked and cooked methods will give you decent results though.