How to build this part using 3d printing
The photo is too small to be clear about the entire objective and there are no dimensions provided. A quick google search returns nothing 3d printer related to "black vera plastics" other than a reference to vera bradley, vera wang and an obscure reference to a woven black carpet with white spots of increasing size. 

Even within those limitations, one can certainly print a strip of black with white dots. One method involves a dual extruder printer, enabling two colors to be printed, one layer at a time. The black layer would be extruded with suitable holes and the white layer would be place within those holes.

Another method involves printing the black layer with holes, swapping out the filament with white and creating white plugs of appropriate sizes for the necessary fit.

You've used the term calibration plate, which implies some level of precision. Is the precision related to spacing, dot size, dot color, or a combination of the above?

Such requirements may make the cost slightly higher, but not excessively. I can print up to to 290 mm long strip, possibly longer by going diagonal on my 290 mm print bed, with or without the two colors done simultaneously.

If you require crisp edges to the white/black transition, the holes-and-plugs method will give best results and require a bit of post processing. It may be necessary to ream the holes to correct diameter and sand the plugs to fit. Dual extrusion rarely provides sharp delineation from one color to the next.