Use Your Eyes.
Many times your eyes are better than many measuring devices or the lack of one.
Here is an example.
Without getting into too much detail I have to set my compound slide on the lathe at angles.
No problem but the people that designed the protractor on the machine didn't put degree marks where they need to be for the angle I want.
Not in the pictuer but the first thing I did when I bought it was to test the sides of the cross slide and the compound slide to see if they are parallel to the dove tail ways they travel on and they are dead on.
Now that it is confirmed I can use the protractor head on my square to set the angle by eyesight by aligning it with the sides of the cross slide.
I tested it with a dial indicator and I was off by less than 0.0005 in about 6 inches of travel.
Now not everyone has a lathe but this method I have used all my life doing all kinds of stuff.
All you have to do to see if something is plumb, level, straight, or square is line it up with something that is by eyesight.
Many times you dont want it to be any of the above but need something to be inline or match something that is already there.
Worth
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