Stan Schaefer wrote:

make hand woodworking cutting tools from O-1, it's really easy to work
in the annealed state and hardens well, even with less-than-optimum
equipment, if you follow the instructions.

I have made many tools from OCS (Old Chevy Spring). Doesn't have to be
Chevy, rally but old leaf or coil springs can be annealed and worked and
oil hardened and tempered.

Ted