Simply added some recesses for magnates 7.9mm x 1.6mm and shortened them to 9mm for use with a laser engraver.  These are simple and easily printable right-angle squares that are useful in all sorts of applications. These were designed to be quick and easy to print, parametric design allows for easy customization, and infinitely useful. These are all marked with the inside length of the arms marked on the tops of the squares to be easily identifiable.

While these are designed to be right angles and perfectly square, they'll only be as square as your machine. If you really need micron accuracy in squareness, they may not be the tools for the job, but for a lot of what I do, they are more than accurate enough.