Since I am generally proportion-deficient when sketching but want my architectural sketches to be somewhat realistic in dimensions, I put together this crude measuring device. I call it a "Measurybob". It is simply a pair of unbroken wooden chop-sticks with markings of 1", 1/2" and 1/4" increments. By holding this at arms length, I can quickly size up the relative dimensions of my sketch subject. It is cheap, handy to carry, easy to replace and can attach nicely to a pocket or bag sleeve.

It sure beats me using just my thumb.
Hope this is useful to others. It has saved me from much embarrassment

when sketching buildings and even people.
Cheers
CyberDave