This is probably not what you were looking for, but my son went through an extreme perfectionism stage between three and four years old. Things I found to be helpful were catchphrases and modelling non-COD behavior. I would make a mistake and say aloud, "Oops. That's okay; everyone makes mistakes sometimes.", and carry on like it was nothing; or, "Oh dear, I made a mistake. But that's okay, I can just put a line through it.". It was hard for me to not have everything perfectly in its place, but I couldn't be a hypocrite! My son is still perfectionist, but only about the important things. I personally think a little perfectionism is a good thing.
