The manufacturing of microstripline PCBs is exactly the same as for any conventional PCB. There are, however, four important things to consider:
1.. Choice of laminate material - dielectric constant, losses, thickness
2.. Choice of copper thickness - critical in the final calculations for the striplines
3.. Choice of finish - generally plating will give more controlled thickness
4.. Choice of solder mask - or even if you use solder mask at all. At microwave frequencies the mask will give you extra losses.
Once you have determined the characteristics of the laminate and copper yo are using, do the calculations to turn the electrical characteristics of your design into a physical realisation.