I need precision parts made of various materials (steel, ceramics, aluminium) with machining processes (polishing, milling, EDM) into various levels of surface finish.
For example, it could be a few steel blocks, each made with EDM, milling, polishing respectively. And the milled blocks are milled into a few roughness levels.
Are there samples like these that are readily available for purchase, like surface comparison blocks. And what are the prices for these samples?