This comes up now and then, the answer is they made a few a long time ago, but I've never seen them, some say they have some. They are very rare, it would be neat if someone could post a pic of the ones they have to show the unicorn exists. People must want them to solve their OCD problems of having them to go with their SAE set, it's not worth trying to track them down. I have the SAE set and I'm not going to bother trying to find any of the metric.