Spring steel such as used on the Wurlitzer bass drum beater is 1095
spring steel available from a host of supply houses.  You need to
know how to work spring steel -- ordinary drill bits will just "skate"
across it.  You need a carbide drill bit or punch press to work the
steel.

The springs that are commonly found on band organs are the outward
pressure springs found in a player piano.  Use the leaf springs found
in a piano supply catalog.

Don Teach