Are you trying to verify that your mic is true? A depth mic cal block/checker/master.
What type of equipment are you working on? I read bearing cover and it caught my eye. I'm a steam turbine tech for DR and I hear those two words just about every day. lol
At my old job we would cover are benches up with cardboard. It help with oils insuch. And it would be easy to change. Just got to watch out with the torch.