When looking into calipers and corner measures, they all have a certain slack, making them quite inaccurate. So I designed a gear-set that has no backlash and should be much more accurate if used in measuring devices. 

PETG would be the best material to print this from as it is best for use with springs. To assemble, put the spring between the 2 points indicated as 1 and 2 under slight tension, minding the orientation of the hooks. Then take the other gear half and pull the spring down a bit with the hook at point 3, rotate it slightly and then pushing them together. Rotate them slightly again before putting them on the axles.