Calibration block in metric units. Contains 11 different 3D printer calibration tests. Model is solid so I recommend printing partial fill.
English units version: http://www.thingiverse.com/thing:217369
Be sure to print 1:1 scale so the tests are accurate! (Assuming your printer is sufficiently calibrated)
horizontal and vertical hole diameters
3-axis feature minimum feature width test
scaling accuracy (via 10mm^3 cube cutout)
rounded feature minimum size
fillet minimum size
Vertical and horizontal max tower height to diameter ratio
Max build hangover angle test (30 - 80 degrees)
minimum layer thickness
Fixed text order on some of the labels.
added a horizontal pillar protrusion test. Yes, that makes it 12 now.
lengthened the minimum layer height test.