Mechanical number counter v2

Same as [Mechanical number counter by jaakkolouhimo](https://www.thingiverse.com/thing:6770782), but set of parts and .stl.

Printing time about 4 hours, weight about 50 grams.


Updates:
CarryGear15.stl: it has inbuilt supports

gear-15-free.stl: the hole diameter in the gear is 0.4 mm larger;