You won't be able to produce materials neither for M1 Garand nor for masks. But at least for N95 masks there are plenty of substitute materials available in abundance if any of the commonly used ones isn't available and complicated stuff is only testing filtration properties of the material with cheap test equipment (you can even make test equipment yourself, it's relatively simple for such purposes, "dust sensor" kind of stuff). Everything else is way more primitive than lathe and mill.