The opening question suggested machinists squares were part of this query, and
while I’ve got wooden try squares up to about 12”, if we’re talking machinists
squares, my biggest has a tongue of 36” and it is so heavy that it takes two men
and a boy to lift, It has it’s own protective box, probably not original,
Similar to this, but made by browne and sharp
http://www.starrett.com/metrology/metrology-products/precision-
measuring-tools/squares/Solid-Squares#currentPage=1&displayMode=grid&itemsPerPag
e=24&sortBy=wp/asc">http://www.starrett.com/metrology/metrology-products
/precision-measuring-tools/squares/Solid-
Squares#currentPage=1&displayMode=grid&itemsPerPage=24&sortBy=wp/asc

It is so large that it can check rafter squares to ensure inside edges are
square with outside edges, and of course inside/outside  edge squareness. with a
high degree of precision, but when I want portability, I just use the 24” tongue
B&S smachinists square.

And now I can drill hang holes in them with my MF 666 devils drill (running and
ducking!)

There are ever so many reasons as to why a try square, or for that matter a
square of any type has been abused, that even if the stock looks pretty with
it’s wood and brass,  that it has to be tested to prove it’s squareness

Eric in cowtown