The gauge is also useful for bending the "air hose" to the proper height.
Not so important, perhaps, if you do not plan to use magnetic uncoupling,
but presumably important if you do.
Laid some of my first track last night. It was tricky because it was
a dual custom curves, 1% grade (1/2" over about 6' or so), and when I
rolled a car on it, it touched another and the couplers clicked together.
Too cool! Lots of switches on each end that need to be flat and level,
too. Nothing like starting simple :-)