Accurate calibration/dimension test

####There is an new version of this: https://www.thingiverse.com/thing:2484766

This test jig is designed to analyse the dimensional accuracy of a printer using engineering methods. But don't be afraid: an excel sheet is included which performs all the math. You just have to print, measure and type in the numbers. A caliper is needed.

Note that calibration is normally not needed for modern printers and calibration cubes are very coarse. Check: https://www.youtube.com/watch?v=Mbn1ckR86Z8