It was fun, but eventually all the colors ran together. I guess if I did it again I might tape the paper to a board so that I could pick it up and swirl it around more.
Here is a detail. Hours later I could drop more vinegar on it, it would fizz some more. The sketchbook was the least exciting, probably because the paper is thinner. It is definitely about process instead of product.
I highly recommend doing this if you are 4 or 5 years old.