How to make a tool to check squareness

How to make a tool to check squareness Squareness Comparator - surface gauge squareness comparator squaremaster surface gauge squareness squareness check checking for square, indicator,measuring parts check a block to see if it is square inspection of perpendicularity STL files download link https://stuconestogacon-my.sharepoint.com/:f:/g/personal/rgallant_conestogac_on_ca/EgbJM0yZwkhNmUourN6eZ1cBdTAo2nSQB-PjBqG_NEayOA?e=TRgtyV