It turns out that USA made .008" carbide end mills are not expensive. I am thinking of cutting a 5.5" quarter circle for the part that holds the polar axis housing. It needs markings for latitude. (The polar axis points to the North Celestial Pole and thus needs adjustment for your latitude.) I would need ideally one degree divisions.
Because of how I need to hold this part when turning a sheet of 6" x 6" into a quarter circle, I will be cutting a 5.5" x 5.5" part. This will give me a 4.31" hemisemicircumference. For 90 one degree divisions, those would be .0479" apart. The ten degree markers will be longer and marked with degrees. (There is a font library in linuxCNC.) The 5 degree lines will be shorter and the one degree markers shorter still. The .0120" end mill should allow clear spaces between degree markers.
These are very thin, and brittle cutting tools. I will be cutting in .0001" cuts (probably to .002" deep) at probably .5 inches/minute until I am sure this is safe. (Yes, I will buy two.)
Once cut, I will use the finest brush that I can to fill in with phosphorescent paint. Then to remove overspray, I will run a flycutter across the surface .001" deep, leaving a painted set of lines.
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