thickness
micrometer
you would probably use a micrometer
Inside Micrometer
for measuring things which are difficult to measure with a ruler
A machinist such as a lathe operator would use a micrometer caliper for precise measurements of the product he is machining, Also used by designers of precision parts and programmers of precision machines.
Micrometer and Vernier
How can I calibrate a micrometer without the use of gage blocks. Any adjustments on the device?
I would use the word engineer.
An engineer
Because it is very accurate.
Millimetres, as in 1.5 mm. You could use a micrometer to measure thickness of a coin.
You could use a simple ruler, or a micrometer for greater accuracy.