I ran across this video this morning:
https://www.youtube.com/watch?v=hnHjrz_inQUI didn't watch the entire video or even completely understand it, but it seems to be a cheap way to measure flatness to a sub-micron level using a cheap laser level and cheap webcam.
If this works as advertised, I wondered if this principle could be used for checking table and way flatness along with other potential precision measurements without the need to buy expensive surface plates or other devices.
Makes one wonder what could be done using a more expensive laser and webcam.
