A scanning photo-lithography process is developed to miniaturize mechanical calculators down to 40 μm in diameter for their calculating micro-gears. Our first moulding process span the dimensions from 1 mm to 60 μm for the micro-gears. Down to 100 μm, the planar calculator construction can still be based on a micro-manipulation of the moving parts under an optical microscope. Below and to reach the 10 μm, a double photo-lithography process was developed on a specific graphite/SiO2/Si wafer for mastering surface frictions. After a baking at 120 °C, the photo-resist becomes the material constitutive of all the moving micromechanical pieces. Only the rotation micro-axles remain metallic to ensure their good anchoring to the surface. A 2-digits micro-calculator is fabricated. In base 10, the carry propagation is demonstrated.