This is a cleaned up symmetric 3D scan of my head it is mm accurate, I use it for making masks and costumes - I use it enough to know it's a good scan. I'm posting it here so that people have it as a resource to model respirators off of.

I want to note that I now have a few additional scans to compare this one to, the neck is on the short side, obviously there is a lot of human variance. So just note that if the neck length on this scan is critical to your project it's on the short side.