3D scanners

Know anything about 3d scanning? Our new HS shop teacher is an
artist, but not a technology guy, so I've been talking to him about
the cnc router I want us to build. He's been luke warm, but when he
mentioned his 3D class yesterday, and I told him I thought that
scanning something – like a face – and then producing it with the yet
to be built router might be within our reach, his eyes lit up. I've
done some research today on homebrew scanners, and found a few college
projects, plus DAVID, but am really starting from scratch, so any
input on the scanning part would be welcomed.