I bought a assorted package of 8"x12" sheets of shim stock that went from .001 to .02"
Very handy and a .001" gauge can be cut from it. Always iron the edges of thin stock after cutting.
I rarely use my 12" set of feelers but multiple sets are useful and one set should have .0015"and .0025" gauges.
These are some of the least expensive tools you will have to buy for your kit.
A dial test indicator in .0005 increments is nice but when your getting into it one that reads tenths is great.
Watch for pieces of carbide stock that can be clamped or brazed to handles as you will find special tools are needed to reach into
those difficult spots as well as material to make your special scraper handles.
You may want to practice on some practical parts so machined cast iron angle brackets are nice.
The machined ones are less expensive and you can scrape all eight surfaces flat and square for practice.
These can then be used for checking machine surfaces.
The large flats on them are good places to practice flaking.
I don't have a surface gauge with the features I would like but will eventually build one.
So, watch for nice pieces of cast iron stock. Even small pieces could be turned into small gibs or other needed parts.
Never pass good cast iron up.
I bought a china 12" tall cylindrical straight edge which has proven very true and handy.
Had to have something to check my work.
One problem, I thought it would be a hollow tube but its solid and I cant even pick it up much of the time.
A six inch tall one would have been better for me.