Brad:
I did some research and went to home depot and got a new framing square there.
They don't seem to be selling the "fat boy" aluminum square any more.
What they have now is an Empire brand framing square which is 3/32" thick instead of the 3/16" thickness of the "fat boy" that I've got. So, I when back to the machine shop and we measured everything very accurately to insure that all "sliders" will fit a standard available framing square.
And we set some tolerances for the production of the slider.
This should make it so that it will fit readily available framing squares and combination square rulers.
And I will include an instruction sheet of how to install it.
I feel every confident now that these will work.

Jim Rogers

Whatever you do, have fun doing it!