Ran across this site with tons of tools for measuring.
http://www.igaging.com/index.html
They don't sell on line so I had to look through woodworking catalogues to find them and they don't always give the brand name. I bought the DigiAlign to set up or check my table saw. Yeah, I know you can make a home made system but I never trusted mine. Also bought the height gage mostly for setting up bit height on the router table, I always take a lot of time and test cuts to get that right. I also bought some set-up blocks from Lee Valley for spacing the router fence mostly. Guess I am just getting too dang old to make a lot of stuff like that. At least until I run out of money