I've made several jigs on 3/4 mdf, I machine it flat and then drill holes every inch to thread inserts, I put the whole board on my machine and it nests itself square, I use an xyz probe with openbuilds blackbox. Use macros to save locations per jig

Hey Nick, great video. Another option that might simplify things would be to use your bracket with the scribed lines to zero X and Y. Then, use the Onefinity user interface to move your bit to 1" in X and 1" in Y. Then, simply zero out x and y again. This would save you having to enlarge your stock on your designs and would be just as repeatable. Cheers.

use a dial test indicator and set xy0 the center

Why not just use a triquetra xyz probe?

let the finished ht be z0