Grinding Shims.

I don't believe shims are through hardened (heat treated), I'm pretty sure they are case hardened, and although that still involves heat it's a lot lower temp

But even case hardening is still going to require grinding.

I am going to see a friend who owns a machine shop, I am going to see what it will take to mfg some shims in different sizes, if there is enough of a market for them I would get him to make a bunch of them