Lot of people I know measure with a piece of string. It does sort of do the job on occasion.
Superstrings on the other hand are a tad more difficult to work with.
At 10 to the power of -33 cm in length (plus or minus a peck multiplied by a rood) it is tricky to find it again if you drop it. Made even more so by it's ability to be in two places at the same time, or to disappear into another Universe altogether and be replaced by an egg plant.